Where does “aisti” come from?

aisti (Finnish) comes from Finnish haisti, from Finnish haistaa, from Proto-Finnic haistadak — to smell.

aisti (Finnish): sense; Third-person singular indicative past form...

Definitions

Step	Language	Word	Meaning
1	Finnish	haisti	olfaction; the sense of smell
2	Finnish	haistaa	to sniff, smell; to scent, smell/nose out, get...
3	Proto-Finnic	haistadak	to smell

aisti — Etymology, Origin & Word History | Etymology Explorer