early 15c., profoundnesse, "inner part of the body;" mid-15c. as "the bottom of the sea;" late 15c. as "depth of meaning, mystery;" from profound + -ness.
Entries linking to profoundness
profound adj.
c. 1300, "characterized by intellectual depth, very learned," from Old French profont, profund (12c., Modern French profond) and directly from Latin profundus "deep, bottomless, vast," also "obscure; profound; immoderate," from pro "forth" (from PIE root *per- (1) "forward") + fundus "bottom" (see fund (n.)).
The literal and figurative senses both were in Latin, but English, having already deep, has employed this word primarily in its figurative sense; however in 15c. it was used of deep lakes or wounds. Sense of "deeply felt, intense" is from c. 1400. Related: Profoundly. A verb profound "to penetrate, reach inside, saturate, fill" is attested in English from 15c.-17c.
-ness
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).