"exalted, of high rank," early 15c. (early 14c. as a surname); also "with a high purpose," from loft (n.) + -y (2). Literal sense of "high" is attested from 1580s. Related: Loftily; loftiness.
Entries linking to lofty
loft n.
"an upper chamber," c. 1300, an extended sense from late Old English loft "the sky; the sphere of the air," from Old Norse lopt (Scandinavian -pt- pronounced like -ft-) "air, sky," originally "upper story, loft, attic," from Proto-Germanic *luftuz "air, sky" (source also of Old English lyft, Dutch lucht, Old High German luft, German Luft, Gothic luftus "air").
If this is correct, the sense development would be from "loft, ceiling" to "sky, air." Buck suggests a further connection with Old High German louft "bark," louba "roof, attic," etc., with development from "bark" to "roof made of bark" to "ceiling," though this did not directly inform the meaning "air, sky" (compare lodge (n.)). But Watkins says this is "probably a separate Germanic root." Meaning "gallery in a church" first attested c. 1500. From 1520s as "apartment over a stable" used for hay storage, etc.
-y 2
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.