1852, "gland-like, resembling a gland," from adenoid + -al (1). From 1919 as "having the appearance of one with adenoids."
Entries linking to adenoidal
adenoid adj.
1839, "gland-like," from medical Latin adenoideus, from Greek adenoeides, from adēn (genitive adēnos) "gland" (see adeno-) + eidos "form" (see -oid). Adenoids (n.) "adenoid growths" is attested by 1856.
-al 1
suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).