One more than two; two and one. 2 Sam. xxiv. 12. [1913 Webster]
" Three is often joined with other words, forming compounds signifying divided into, composed of, or containing, three parts, portions, organs, or the like; as, three-branched, three-capsuled, three-celled, three-cleft, three-edged, three-foot, three-footed, three-forked, three-grained, three-headed, three-legged, three-mouthed, three-nooked, three-petaled, three-pronged, three-ribbed, three-seeded, three-stringed, three-toed, and the like." [1913 Webster]
"Three solemn aisles approach the shrine." [1913 Webster]

1.  The number greater by a unit than two; three units or objects. [1913 Webster]

2.  A symbol representing three units, as 3 or iii. [1913 Webster]

three, n. & adj.
--n.
1 a one more than two, or seven less than ten. b a symbol for this (3, iii, III).
2 a size etc. denoted by three.
3 the time of three o'clock.
4 a set of three.
5 a card with three pips.
--adj. that amount to three.

Idiom:
three-card trick a game in which bets are made on which is the queen among three cards lying face downwards. three cheers see CHEER. three-colour process a process of reproducing natural colours by combining photographic images in the three primary colours. three-cornered
1 triangular.
2 (of a contest etc.) between three parties as individuals.
three-decker
1 a warship with three gun-decks.
2 a novel in three volumes.
3 a sandwich with three slices of bread. three-dimensional having or appearing to have length, breadth, and depth.
three-handed
1 having or using three hands.
2 involving three players. three-legged race a running-race between pairs, one member of each pair having the left leg tied to the right leg of the other. three-line whip a written notice, underlined three times to denote urgency, to members of a political party to attend a parliamentary vote. three parts three quarters. three-phase see PHASE. three-piece consisting of three items (esp. of a suit of clothes or a suite of furniture). three-ply adj. of three strands, webs, or thicknesses.
--n.
1 three-ply wool.
2 three-ply wood made by gluing together three layers with the grain in different directions. three-point landing Aeron. the landing of an aircraft on the two main wheels and the tail wheel or skid simultaneously. three-point turn a method of turning a vehicle round in a narrow space by moving forwards, backwards, and forwards again in a sequence of arcs. three-quarter n. (also three-quarter back) Rugby Football any of three or four players just behind the half-backs.
--adj.
1 consisting of three-fourths of something.
2 (of a portrait) going down to the hips or showing three-fourths of the face (between full face and profile). three-quarters three parts out of four. three-ring circus esp.
US
1 a circus with three rings for simultaneous performances.
2 an extravagant display. the three Rs reading, writing, and arithmetic, regarded as the fundamentals of learning. three-way involving three ways or participants. three-wheeler a vehicle with three wheels.

Etymology:
OE thri f. Gmc

N  triality, trinity, triunity, three, triad, triplet, trey, trio, ternion, leash, shamrock, tierce, spike-team, trefoil, triangle, trident, triennium, trigon, trinomial, trionym, triplopia, tripod, trireme, triseme, triskele, triskelion, trisula, third power, cube, cube root, three, triform, trinal, trinomial, tertiary, ternary, triune, triarch, triadie, triple, tri-, tris-, tria juncta in uno, triality, trinity, triunity, three, triad, triplet, trey, trio, ternion, leash, shamrock, tierce, spike-team, trefoil, triangle, trident, triennium, trigon, trinomial, trionym, triplopia, tripod, trireme, triseme, triskele, triskelion, trisula, third power, cube, cube root, three, triform, trinal, trinomial, tertiary, ternary, triune, triarch, triadie, triple, tri-, tris-, tria juncta in uno.

prayer of azariah and song of the three children, three dimensional, three hundred, three kings' day, three times, three weird sisters, three year old