sell vs transact

sell is a noun but transact is not a noun.

Word	Noun	Adjective	Verb	Adverb
sell	Yes	No	Yes	No
transact	No	No	Yes	No

As verbs, transact is a hypernym of sell; that is, transact is a word with a broader meaning than sell:

sell (noun)	transact (noun)
the activity of persuading someone to buy

sell (verb)	transact (verb)
persuade somebody to accept something	conduct business
exchange or deliver for money or its equivalent
do business; offer for sale as for one's livelihood
give up for a price or reward
deliver to an enemy by treachery
be sold at a certain price or in a certain way
be responsible for the sale of
be approved of or gain acceptance