"pertaining to or of the nature of a colloid," 1859, from colloid + -al (1).
Entries linking to colloidal
colloid n.
1854, "a substance in a gelatinous or gluey state," from French colloide (1845), from Greek kolla "glue," which is of uncertain origin, + -oeidēs "form" (see -oid). Also an adjective, "like glue or jelly."
-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)).