Cydweitho, v. to co-operate
Cydweithiwr, n. a fellow labourer
Cydweithredu, v. to co-operate
Cydwelydd, n. a consociate
Cydwerth, n. an equivalent
Cydweu, v. to interweave
Cydwybod, n. conscience
Cydwybodol, a. conscientious
Cydwybodolrwydd, n. conscientiousness
Cydwynebiad, n. confrontation