Sept or hept
The prefix hepta- means seven. A heptagon is a polygon with seven sides. Other words that have this same prefix are: heptathlon, heptameter, herpetology, heptarch, heptads.
The prefix for inadequate is in-. The prefix in- means not.
The prefix is poly-. This prefix means many.
The prefix in non-. This prefix means not.
The prefix in the word "atheist" is "a-", which means "without" or "not."
The prefix in the word "confide" is "con-," which means "with" or "together."
The prefix of "heptathlon" is "hept-" which means seven.
The prefix a- means NOT. In the word amoral it means the opposite of moral.
sept
an- means "not"
The prefix ben- means good.
The prefix in the word maladjusted is mal-. This prefix means bad.