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.-rare; not dense or thick; -- applied to fluids or soft mixtures; as, thin blood; thin broth; thin air.-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.-not full or well grown; wanting in plumpness.-not stout; slim; slender; lean; gaunt; as, a person becomes thin by disease.-wanting in body or volume; small; feeble; not full.-slight; small; slender; flimsy; wanting substance or depth or force; superficial; inadequate; not sufficient for a covering; as, a thin disguise.-not thickly or closely; in a seattered state; as, seed sown thin.-to make thin (in any of the senses of the adjective).-to grow or become thin; -- used with some adverbs, as out, away, etc.; as, geological strata thin out, i. e., gradually diminish in thickness until they disappear.