anosmia (n.)youdaoicibaDictYouDict
"loss of sense of smell," 1811, Modern Latin, from Greek an-, privative prefix (see an- (1)), + osme "smell" (Doric odme), from *odsme, cognate with Latin odor (see odor) + abstract noun ending -ia.
flair (n.)youdaoicibaDictYouDict
mid-14c., "an odor," from Old French flaire "odor or scent," especially in hunting, "fragrance, sense of smell," from flairier "to give off an odor; stink; smell sweetly" (Modern French flairer), from Vulgar Latin *flagrare, dissimilated from Latin fragrare "emit (a sweet) odor" (see fragrant). Sense of "special aptitude" is American English, 1925, probably from hunting and the notion of a hound's ability to track scent.
flavor (n.)youdaoicibaDictYouDict
c. 1300, "a smell, odor" (usually a pleasing one), from Old French flaor "smell, odor; action of smelling, sense of smell," probably from Vulgar Latin flator "odor," literally "that which blows," in classical Latin "blower," from flare "to blow, puff," which is cognate with Old English blawan (see blow (v.1)).

"Not common before Milton's time" [Century Dictionary], and it is not clear what exactly Milton meant when he used it. The same Vulgar Latin source produced Old Italian fiatore "a bad odor." Sense of "taste, savor" is 1690s, perhaps 1670s; originally "the element in taste which depends on the sense of smell." The -v- in the English word is euphonic or perhaps from influence of savor. Flavor-of-the-month is from 1946 (originally of ice cream).
nasal (adj.)youdaoicibaDictYouDict
1650s, "of the nose," from French nasal, from Latin nasus "nose, the nose, sense of smell," from PIE *nas- (see nose (n.)). Of speech sounds, attested from 1660s. As a noun, "nasal letter or sound," from 1660s. Related: Nasality; nasalization.
sagacity (n.)youdaoicibaDictYouDict
c. 1500, from Middle French sagacité, from Latin sagacitatem (nominative sagacitas) "keenness of perception, quality of being acute," from sagax (genitive sagacis) "of quick perception, acute," related to sagus "prophetic," sagire "perceive keenly," from PIE root *sag- "to track down, trace, seek" (cognates: Old English secan "to seek;" see seek). Also used 17c.-18c. of animals, meaning "acute sense of smell."