/ Dictionary / Index A ailanthus: Meaning and Definition of Find definitions for: ai•lan•thus Pronunciation: (ā-lan'thus), [key] — pl. -thus•es. any tree belonging to the genus Ailanthus, of the quassia family, esp. A. altissima, widely grown in cities. Cf. tree of heaven. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: ailanthus (Thesaurus) ail ailanthus silkworm Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language