saltiness (n.)

mid-15c., salti, "tasting of salt, somewhat salt, impregnated with salt," from salt (n.) + -y (2).

The meaning "racy, sexy" is from 1866, from salt in the sense of "that which gives life or pungency" (1570s, originally in reference to words or wit); salt (adj.) also was used of lecherous (female) dogs, etc. (1540s) and also of persons (16c.-17c.).

The U.S. slang sense of "angry, irritated" is first attested 1938 (perhaps from similar use with regard to sailors, "tough, aggressive," which is attested by 1920), especially in phrase jump salty "unexpectedly become enraged" (1938). Related: Saltily.

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).