1.  observation(n = noun.act) - the act of making and recording a measurement;
is a kind of measure, measurement, measuring, mensuration
has particulars: radio observation
Derived forms verb observe₈, verb observe₁

2.  observation(n = noun.act) observance, watching - the act of observing; taking a patient look;
is a kind of look, looking, looking at
has particulars: monitoring, sighting, stargazing
Derived forms verb observe₈, verb observe₃, verb observe₄, verb observe₇

3.  observation(n = noun.communication) reflection, reflexion - a remark expressing careful consideration;
is a kind of comment, input, remark
has particulars: parkinson's law, parkinson's law
Derived forms verb observe₈, verb observe₃, verb observe₁, verb observe₄, verb observe₇

4.  observation(n = noun.cognition) - facts learned by observing; "he reported his observations to the mayor"
is a kind of fact
has particulars: scientific fact
Derived forms verb observe₈, verb observe₃, verb observe₁, verb observe₄, verb observe₇

5.  observation(n = noun.cognition) notice, observance - the act of noticing or paying attention; "he escaped the notice of the police"
is a kind of attending, attention
has particulars: mind, remark
Derived forms verb observe₈, verb observe₂, verb observe₃, verb observe₄, verb observe₇

1.  The act or the faculty of observing or taking notice; the act of seeing, or of fixing the mind upon, anything. [1913 Webster]
"My observation, which very seldom lies." [1913 Webster]

2.  The result of an act, or of acts, of observing; view; reflection; conclusion; judgment. [1913 Webster]
"In matters of human prudence, we shall find the greatest advantage in making wise observations on our conduct." [1913 Webster]

3.  An expression of an opinion or judgment upon what one has observed; a remark. Shak. [1913 Webster]
"To observations which ourselves we make
We grow more partial for the observer's sake." [1913 Webster]

4.  Performance of what is prescribed; adherence in practice; observance. [1913 Webster]
"We are to procure dispensation or leave to omit the observation of it in such circumstances." [1913 Webster]

5.  The act of recognizing and noting some fact or occurrence in nature, as an aurora, a corona, or the structure of an animal. [1913 Webster]
" When a phenomenon is scrutinized as it occurs in nature, the act is termed an observation. When the conditions under which the phenomenon occurs are artificial, or arranged beforehand by the observer, the process is called an experiment. Experiment includes observation." [1913 Webster]

observation, n.
1 the act or an instance of noticing; the condition of being noticed.
2 perception; the faculty of taking notice.
3 a remark or statement, esp. one that is of the nature of a comment.
4 a the accurate watching and noting of phenomena as they occur in nature with regard to cause and effect or mutual relations. b the noting of the symptoms of a patient, the behaviour of a suspect, etc.
5 the taking of the sun's or another heavenly body's altitude to find a latitude or longitude.
6 Mil. the watching of a fortress or hostile position or movements.

Idiom:
observation car esp. US a carriage in a train built so as to afford good views. observation post Mil. a post for watching the effect of artillery fire etc. under observation being watched.

Derivative:
observational adj. observationally adv.

Etymology:
ME f. L observatio (as OBSERVE)

N  intellect, mind, understanding, reason, thinking principle, rationality, cogitative faculties, cognitive faculties, discursive faculties, reasoning faculties, intellectual faculties, faculties, senses, consciousness, observation, percipience, intelligence, intellection, intuition, association of ideas, instinct, conception, judgment, wits, parts, capacity, intellectuality, genius, brains, cognitive powers, intellectual powers, wit, ability, wisdom, Vernunft, Verstand, soul, spirit, ghost, inner man, heart, breast, bosom, penetralia mentis, divina particula aurae, heart's core, the Absolute, psyche, subliminal consciousness, supreme principle, brain, organ of thought, seat of thought, sensorium, sensory, head, headpiece, pate, noddle, noggin, skull, scull, pericranium, cerebrum, cranium, brainpan, sconce, upper story, central processing unit, CPU, arithmetic and logical unit, ALU, metaphysics, psychics, psychology, ideology, mental philosophy, moral philosophy, philosophy of the mind, pneumatology, phrenology, craniology, cranioscopy, ideality, idealism, transcendentalism, spiritualism, immateriality, universal concept, universal conception, metaphysician, psychologist, intellectual, mental, rational, subjective, metaphysical, nooscopic, spiritual, ghostly, psychical, psychological, cerebral, animastic, brainy, hyperphysical, superphysical, subconscious, subliminal, immaterial, endowed with reason, in petto, ens rationis, frons est animi janua, locos y ninos dicen la verdad, mens sola loco non exulat, my mind is my kingdom, stern men with empires in their brains, the mind, the music breathing from her face, thou living ray of intellectual Fire.

N  idea, notion, conception, thought, apprehension, impression, perception, image, eidolon, sentiment, reflection, observation, consideration, abstract idea, archetype, formative notion, guiding conception, organizing conception, image in the mind, regulative principle, view, theory, conceit, fancy, phantasy, point of view, field of view.

N  attention, mindfulness, presence of mind, intentness, intentiveness, alertness, thought, advertence, advertency, observance, observation, consideration, reflection, perpension, heed, heedfulness, particularity, notice, regard, circumspection, diligence, study, scrutiny inspection, introspection, revision, revisal, active application, diligent application, exclusive application, minute application, close application, intense application, deep application, profound application, abstract application, labored application, deliberate application, active attention, diligent attention, exclusive attention, minute attention, close attention, intense attention, deep attention, profound attention, abstract attention, labored attention, deliberate attention, active thought, diligent thought, exclusive thought, minute thought, close thought, intense thought, deep thought, profound thought, abstract thought, labored thought, deliberate thought, active study, diligent study, exclusive study, minute study, close study, intense study, deep study, profound study, abstract study, labored study, deliberate study, minuteness, attention to detail, absorption of mind, indication, calling attention to, attentive, mindful, observant, regardful, alive to, awake to, observing, alert, open-eyed, intent on, taken up with, occupied with, engaged in, engrossed in, wrapped in, absorbed, rapt, transfixed, riveted, mesmerized, hypnotized, glued to (the TV, the window, a book), breathless, preoccupied, watchful, breathless, undistracted, upon the stretch, on the watch, steadfast, interesting, engrossing, mesmerizing, riveting, Int, see!, look, look here, look you, look to it!, mark!, lo!, behold!, soho!, hark, hark ye!, mind!, halloo!, observe!, lo and behold!, attention!, nota bene, N, B, note well, I'd have you to know, notice!, O yes!, Oyez!, dekko!, ecco!, yoho!, this is to give notice, these are to give notice, dictum sapienti sat est, a word to the wise is sufficient, finem respice, Attention! Now hear this! Oyez!, Achtung, vnimanie, chui.

N  affirmance, affirmation, statement, allegation, assertion, predication, declaration, word, averment, confirmation, asseveration, adjuration, swearing, oath, affidavit, deposition, avouchment, assurance, protest, protestation, profession, acknowledgment, legal pledge, pronouncement, solemn averment, solemn avowal, solemn declaration, remark, observation, position, saying, dictum, sentence, ipse dixit, emphasis, weight, dogmatism, dogmatics, asserting, declaratory, predicatory, pronunciative, affirmative, soi-disant, positive, certain, express, explicit, absolute, emphatic, flat, broad, round, pointed, marked, distinct, decided, confident, trenchant, dogmatic, definitive, formal, solemn, categorical, peremptory, unretracted, predicable, affirmatively, in the affirmative, with emphasis, ex-cathedra, without fear of contradiction, as God is my witness, I must say, indeed, i' faith, let me tell you, why, give me leave to say, marry, you may be sure, I'd have you to know, upon my word, upon my honor, by my troth, egad, I assure you, by jingo, by Jove, by George, troth, seriously, sadly, in sadness, in sober sadness, in truth, in earnest, of a truth, truly, perdy, in all conscience, upon oath, be assured, yes, I'll warrant, I'll warrant you, I'll engage, I'll answer for it, I'll be bound, I'll venture to say, I'll take my oath, in fact, forsooth, joking apart, so help me God, not to mince the matter, quoth he, dixi.

meteorological observation post, observation car, observation deck, observation dome, observation post, observation station, observation tower, radio observation, through empirical observation