Cogent
Convincing, reasonable
Colloquial
Informal , vernacular
Combative
Marked by an eagerness to fight
Conciliatory
Appeasing, compatable
Concise
Tight and terse, get to the point no elaborate description!
Condemnatory
Critical, dooming
Condescending
Treating people as weak or inferior
Confessional
Apologetic and penitent
Contemplative
Marked by or given to steady regard/reflection
Contemptuous
Feeling hatred, scornful
Convoluted
Intricate, complicated and tangled, can be used to describe the style of legal contracts
Circumspect
Cautious, careful to consider all circumstances