I. adjective
1.
not thick, heavy, or broad (as in configuration or physique)
a thin body
Synonyms: attenuate, reedy, slender, slight, slim, squinny, stalky, tenuous, twiggy; compare lean
Related Word: lank, lanky, lathy, lean, macilent, spare; cadaverous, gaunt, pinched, skeletal, wasted; meager, puny, small, twiglike
Contrasted words: broad, wide; compact, dense, solid; heavy, massive; corpulent, fat, obese
Antonyms: thick
2.
characterized by wide separation of component particles
thin air at high altitudes
Synonyms: attenuate, attenuated, rare, rarefied, subtile, subtle, tenuous
Related Word: diffuse, diluted, dispersed; fine, refined
Contrasted words: heavy, thick
Antonyms: dense
3.
Synonyms: dilute , diluted, washy, watered-down, waterish, watery, weak
4.
Synonyms: acute 4, argute, high, piercing, piping, sharp, shrill, treble
Related Word: high-pitched
Contrasted words: low, low-pitched; guttural; deep
5.
Synonyms: implausible , flimsy, improbable, inconceivable, incredible, thick, unbelievable, unconvincing, unsubstantial, weak
Related Word: vapid; transparent; questionable; untenable
Idioms: a bit thin
Contrasted words: believable, convincing, sound, substantial
II. verb
1.
to make thin or thinner
a once powerful frame thinned by privation
Synonyms: attenuate, extenuate, wiredraw
Related Word: diminish, reduce; weaken
Contrasted words: broaden, enlarge; strengthen
Antonyms: thicken
2.
to make or become less dense
the air thinned at high altitudes
Synonyms: attenuate, rarefy
Antonyms: densify
3.
Synonyms: dilute , cut, weaken