Ant. Opponent; stranger, alien.
Concatenation. Connection, continuity; series, chain, succession.
Ant. Intermission, severing, disconnection.
Concave. Hollow, depressed, excavated.
Ant. Convex, protuberant, tumular.
Conceal. Hide, suppress, secrete, disguise.
Ant. Reveal, expose, make manifest, lay bare, confess, publish, divulge.
Concede. Surrender, admit, resign, yield, allow.
Ant. Refuse, claim, contend, contradict, deny, contest.
Conceit. Notion, whim, vagary, idea, abstraction, affectation, imagination.