| canonical(proper, just, valid, legal, legitimate) |
| cerebral(adjective, sound, sensible, rational, intelligent) |
| circumspect(moderate, honest, proper, reasoning, intellectual) |
| clear(sound, reasonable, sensible, rational, logical) |
| clear-cut(adjective, sound, sensible, rational, intelligent) |
| cognitive(adjective, sound, sensible, rational, intelligent) |
| coherent(clear, sound, simple, reasonable, sensible) |
| commonsensical(adjective, clear, sound, reasonable, sensible) |
| compelling(clear, sound, reasonable, sensible, rational) |
| conceivable |
| congruent(clear, sound, reasonable, sensible, rational) |
| conscious(adjective, sound, sensible, rational, intelligent) |
| consequent(adjective, clear, sound, reasonable, sensible) |
| consistent(adjective, clear, sound, reasonable, sensible) |
| convincing(clear, sound, reasonable, sensible, rational) |
| cool(adjective, sound, sensible, rational, intelligent) |
| deducible(clear, sound, reasonable, sensible, rational) |
| discerning(clear, sound, reasonable, sensible, rational) |
| discriminating(clear, sound, reasonable, sensible, rational) |
| dispensable |