WordNet sense 1 (of relatively small extent from one surface to the opposite or in cross section):

thin

WordNet sense 2 (not wide):

narrow

WordNet sense 3 (small in quantity):

slim

WordNet sense 4 (limited or below average in number or quantity or magnitude or extent):

little, small

WordNet sense 5 (moving and bending with ease):

lissom, lissome, lithe, lithesome, supple, svelte, sylphlike

WordNet sense 6 (being of delicate or slender build):

slight

WordNet sense 7 (lacking excess flesh):

lean