-fend, fend-, fen-

(Latin: ward off, to ward off, strike, keep off, guard, protect; from fendere [found only in compounded words])

offensive (s) (noun), offensives (pl)
offensive (adjective), more offensive, most offensive
offensively (adverb), more offensively, most offensively
offensiveness (s) (noun) (usually not used in the plural)
undefendable (adjective), more undefendable, most undefendable