[circumstances alter cases] {formal} The way things are, or happen, may […]

[circus] See: [THREE-RING CIRCUS].

[CiS] "Chuckle(ing) in Silence", "chuckling very quietly"; as an alternative to […]

[citizen] See: [SENIOR CITIZEN].

[civil] See: [KEEP A CIVIL TONGUE IN ONE'S HEAD].

[claim] See: [STAKE A CLAIM].

[claim check] {n.} A ticket needed to get back something. * […]

[clam up] {v.}, {slang} To refuse to say anything more; stop […]

[clamp down] {v.}, {informal} To put on strict controls; enforce rules […]

[class] See: [HIGH-CLASS], [SECOND CLASS].