Source : Webster's Revised Unabridged Dictionary (1913)

Thin \Thin\, adv.
   Not thickly or closely; in a seattered state; as, seed sown
   thin.

         Spain is thin sown of people.            --Bacon.

Thin \Thin\, v. t. [imp. & p. p. {Thinned}; p. pr. & vb. n.
   {Thinning}.] [Cf. AS. ge[thorn]ynnian.]
   To make thin (in any of the senses of the adjective).

Thin \Thin\, v. i.
   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.

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.
                                                  --Addison.

   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.
                                                  --Dryden.

   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}.

Source : WordNet®

thin
     adj 1: of relatively small extent from one surface to the opposite
            or in cross section; "thin wire"; "a thin chiffon
            blouse"; "a thin book"; "a thin layer of paint" [ant:
            {thick}]
     2: lacking excess flesh; "you can't be too rich or too thin";
        "Yon Cassius has a lean and hungry look"-Shakespeare [syn:
         {lean}] [ant: {fat}]
     3: very narrow; "a thin line across the page" [syn: {slender}]
     4: having little substance or significance; "a flimsy excuse";
        "slight evidence"; "a tenuous argument"; "a thin plot"
        [syn: {flimsy}, {slight}, {tenuous}]
     5: not dense; "a thin beard"; "trees were sparse" [syn: {sparse}]
     6: relatively thin in consistency or low in density; not
        viscous; "air is thin at high altitudes"; "a thin soup";
        "skimmed milk is much thinner than whole milk"; "thin oil"
        [ant: {thick}]
     7: (of sound) lacking resonance or volume; "a thin feeble cry"
        [ant: {full}]
     8: lacking spirit or sincere effort; "a thin smile"
     [also: {thinning}, {thinned}, {thinnest}, {thinner}]

thin
     adv : without viscosity; "the blood was flowing thin" [syn: {thinly}]
           [ant: {thickly}]
     [also: {thinning}, {thinned}, {thinnest}, {thinner}]

thin
     v 1: lose thickness; become thin or thinner [ant: {thicken}]
     2: make thin or thinner; "Thin the solution" [ant: {thicken}]
     3: lessen the strength or flavor of a solution or mixture; "cut
        bourbon" [syn: {dilute}, {thin out}, {reduce}, {cut}]
     4: take off weight [syn: {reduce}, {melt off}, {lose weight}, {slim},
         {slenderize}, {slim down}] [ant: {gain}]
     [also: {thinning}, {thinned}, {thinnest}, {thinner}]