Cydgyfaneddwr, a joint occupier
Cydgyfarch, v. to congratulate
Cydgyfarfod, n. coincidency
Cydgyfartaledd, n. co-equalty
Cydgyfathrach, n. consociation
Cydgyfranogi, v. to intercomunicate
Cydgylchiad, n. convolution
Cydgyrchu, v. to assemble together
Cydgyrhaeddiad, co-existension
Cydhanfod, n. co-existence