1650s, "serving as a residence," from resident (n.) + -ial. Meaning "pertaining to residents, having to do with housing" is by 1856.
Entries linking to residential
resident n.
mid-15c., "an inhabitant, one who dwells in a place permanently or for a considerable time," from resident (adj.). Meaning "medical graduate doing supervised specialized practice in a hospital as training" is attested by 1892, American English.
-ial
adjectival word-forming element, variant of -al (1) with connective -i-. From Latin -ialis, in which the -i- originally was from the stem of the word being attached but later came to be felt as connective.