The Collaborative International Dictionary of English v.0.48:
Thin \Thin\, a. [Compar. Thiner; superl. Thinest.] [OE.
thinne, thenne, thunne, AS. [thorn]ynne; akin to D. dun, G.
d["u]nn, OHG. dunni, Icel. [thorn]unnr, Sw. tunn, Dan. tynd,
Gael. & Ir. tana, W. teneu, L. tenuis, Gr. ? (in comp.)
stretched out, ? stretched, stretched out, long, Skr. tanu
thin, slender; also to AS. ?enian to extend, G. dehnen, Icel.
?enja, Goth. ?anjan (in comp.), L. tendere to stretch, tenere
to hold, Gr. ? to stretch, Skr. tan. [root]51 & 237. Cf.
Attenuate, Dance, Tempt, Tenable, Tend to move,
Tenous, Thunder, Tone.]
1. Having little thickness or extent from one surface to its
opposite; as, a thin plate of metal; thin paper; a thin
board; a thin covering.
2. Rare; not dense or thick; -- applied to fluids or soft
mixtures; as, thin blood; thin broth; thin air. --Shak.
In the day, when the air is more thin. --Bacon.
Satan, bowing low
His gray dissimulation, disappeared,
Into thin air diffused. --Milton.
3. Not close; not crowded; not filling the space; not having
the individuals of which the thing is composed in a close
or compact state; hence, not abundant; as, the trees of a
forest are thin; the corn or grass is thin.
Ferrara is very large, but extremely thin of people.
4. Not full or well grown; wanting in plumpness.
Seven thin ears . . . blasted with the east wind.
--Gen. xli. 6.
5. Not stout; slim; slender; lean; gaunt; as, a person
becomes thin by disease.
6. Wanting in body or volume; small; feeble; not full.
Thin, hollow sounds, and lamentable screams.
7. Slight; small; slender; flimsy; wanting substance or depth
or force; superficial; inadequate; not sufficient for a
covering; as, a thin disguise.
My tale is done, for my wit is but thin. --Chaucer.
Note: Thin is used in the formation of compounds which are
mostly self-explaining; as, thin-faced, thin-lipped,
thin-peopled, thin-shelled, and the like.
Thin section. See under Section.