(1):

(v. t.) To tinge with sallowness.

(2):

(superl.) Having a yellowish color; of a pale, sickly color, tinged with yellow; as, a sallow skin.

(3):

(n.) The willow; willow twigs.

(4):

(n.) A name given to certain species of willow, especially those which do not have flexible shoots, as Salix caprea, S. cinerea, etc.