1.  retardation(n = noun.attribute) deceleration, slowing - a decrease in rate of change; "the deceleration of the arms race"
is a kind of alteration, change, modification
Derived forms verb retard₄, verb retard₂

2.  retardation(n = noun.time) Array - the extent to which something is delayed or held back; Array
is a kind of delay, hold, postponement, time lag, wait
Derived form verb retard₂

3.  retardation(n = noun.object) retardant, retardent - any agent that retards or delays or hinders; "flame-retardant"
is a kind of agent
Derived form verb retard₁

4.  retardation(n = noun.cognition) backwardness, mental retardation, slowness, subnormality - lack of normal development of intellectual capacities; Array
is a kind of stupidity
has particulars: abnormality, mental defectiveness, mental deficiency, moronity, amentia, idiocy, imbecility
Derived form verb retard₃

5.  retardation(n = noun.act) lag, slowdown - the act of slowing down or falling behind; Array
is a kind of delay, holdup
Derived forms verb retard₄, verb retard₂

1.  The act of retarding; hindrance; the act of delaying; as, the retardation of the motion of a ship; -- opposed to acceleration. [1913 Webster]
"The retardations of our fluent motion." [1913 Webster]

2.  That which retards; an obstacle; an obstruction. [1913 Webster]
"Hills, sloughs, and other terrestrial retardations." [1913 Webster]

3.  The keeping back of an approaching consonant chord by prolonging one or more tones of a previous chord into the intermediate chord which follows; -- differing from suspension by resolving upwards instead of downwards. [1913 Webster]

4.  The extent to which anything is retarded; the amount of retarding or delay. [1913 Webster]

N  hindrance, prevention, preclusion, obstruction, stoppage, embolus, embolism, infarct, interruption, interception, interclusion, hindrance, impedition, retardment, retardation, embarrassment, oppilation, coarctation, stricture, restriction, restraint, inhibition, blockade, interference, interposition, obtrusion, discouragement, discountenance, impediment, let, obstacle, obstruction, knot, knag, check, hitch, contretemps, screw loose, grit in the oil, bar, stile, barrier, turnstile, turnpike, gate, portcullis, beaver dam, trocha, barricade, wall, dead wall, sea wall, levee breakwater, groyne, bulkhead, block, buffer, stopper, boom, dam, weir, burrock, drawback, objection, stumbling-block, stumbling-stone, lion in the path, snag, snags and sawyers, encumbrance, incumbrance, clog, skid, shoe, spoke, drag, drag chain, drag weight, stay, stop, preventive, prophylactic, load, burden, fardel, onus, millstone round one's neck, impedimenta, dead weight, lumber, pack, nightmare, Ephialtes, incubus, old man of the sea, remora, difficulty, insuperable, obstacle, estoppel, ill wind, head wind, trammel, tether, hold back, counterpoise, damper, wet blanket, hinderer, marplot, killjoy, party pooper, party crasher, interloper, trail of a red herring, opponent, hindering, obstructive, obstruent, impeditive, impedient, intercipient, prophylactic, impedimentary, in the way of, unfavorable, onerous, burdensome, cumbrous, cumbersome, obtrusive, hindered, windbound, waterlogged, heavy laden, hard pressed, unassisted &c (assist), single-handed, alone, deserted, occurrent nubes.

N  lateness, tardiness, delay, delation, cunctation, procrastination, deferring, deferral, postponement, adjournment, prorogation, retardation, respite, pause, reprieve, stay of execution, protraction, prolongation, Fabian policy, medecine expectante, chancery suit, federal case, leeway, high time, moratorium, holdover, late, tardy, slow, behindhand, serotine, belated, postliminious, posthumous, backward, unpunctual, untimely, delayed, postponed, dilatory, delayed, in abeyance, late, lateward, backward, late in the day, at sunset, at the eleventh hour, at length, at last, ultimately, after time, behind time, after the deadline, too late, too late for, slowly, leisurely, deliberately, at one's leisure, ex post facto, sine die, nonum prematur in annum, against the sunbeams serotine and lucent, ie meglio tardi che mai, deliberando saepe perit occasio.

N  slowness, languor, drawl, creeping, lentor, retardation, slackening, delay, claudication, jog trot, dog trot, mincing steps, slow march, slow time, slow goer, slow coach, slow back, lingerer, loiterer, sluggard, tortoise, snail, poke, dawdle, slow, slack, tardy, dilatory, gentle, easy, leisurely, deliberate, gradual, insensible, imperceptible, glacial, languid, sluggish, slow paced, tardigrade, snail-like, creeping, reptatorial, slowly, leisurely, piano, adagio, largo, larghetto, at half speed, under easy sail, at a foots pace, at a snail's pace, at a funeral pace, in slow time, with mincing steps, with clipped wings, haud passibus aequis, gradually, gradatim, by degrees, by slow degrees, by inches, by little and little, step by step, one step at a time, inch by inch, bit by bit, little by little, seriatim, consecutively, dum Roma deliberat Saguntum perit, at a glacial pace.

mental retardation