de·fend / diˈfend/ • v. [tr.] resist an attack made on (someone or something); protect from harm or danger. ∎  speak or write in favor of (an action or person); attempt to justify: he defended his policy. ∎  conduct the case for (the party being accused or sued) in a lawsuit: a lawyer who defends dissidents. ∎  compete to retain (a title or seat) in a contest or election: he successfully defended his Congressional seat [as adj.] (defending) the defending champion. ∎  [intr.] (in sports) protect one's goal rather than attempt to score against one's opponents.DERIVATIVES: de·fend·a·ble adj.

defend guard from attack; †ward off, prevent, prohibit XIII; vindicate (a cause, person) XV. — (O)F. défendre :- L. dēfendere ward off, protect, f. DE- 2 + -fendere (only in comps.).
So defendant XIV. — (O)F. défendant, sb. use of prp. of défendre. defender XIII. — AN. defendour; see -ER 2. defence, U.S. defense XIII. ME. defens and defense, -ence — OF. defens and (also mod.) défense — L. (Rom.) dēfēnsum, dēfēnsa, sb. uses of n. and fem. pp. of dēfendere. defensible †defensive; defendable, justifiable. XV. late L. dēfēnsibilis, f. dēfēns-, pp. stem of dēfendere.