"making or causing to smell; having the sense of smell," 1650s, from Latin olfactorius, from olfact-, past-participle stem of olfacere "to get the smell of, sniff," from olere "emit a smell, give off a smell of" (see odor) + facere "to make" (from PIE root *dhe- "to set, put").
Oleg
oleo
oleo-
oleomargarine
olfaction
olfactory
Olga
oligarch
oligarchic
oligarchy
oligo-