| Word element | Meaning | Example of use (sound file links underlined) |
|---|---|---|
| caban | hut | Caban-coch |
| cadair, cader | seat, stronghold | Cadair Idris |
| Cadfan | saint's name | |
| cae, (plural caeau) | field, enclosure | Pen-y-cae |
| caer, (plural caerau) | fort, stronghold | Caersws |
| caled | hard | |
| cam | crooked | |
| canol | middle | Ty-canol |
| cantref | district | |
| capel | chapel, meeting house | Capel Curig |
| carn, (plural carnau) | cairn, rock, mountain | |
| carnedd, (plural carneddan, carneddi) | cairn, barrow, tumulus, mountain | |
| carreg, (plural cerrig) | stone, rock | Carreg Cennen |
| carrog | torrent | |
| cartre(f) | home | |
| cas | (as in Cas-bach} castle | Cas-newydd (Newport) |
| castell | castle, stronghold | Castell Caereinion |
| cawr, (plural cewri) | giant | |
| cefn | ridge | Cefn Cribwr |
| cegin | kitchen | |
| cei | quay | |
| ceiliog | cock | |
| Ceiriog | name of a river in Denbighshire | Afon Ceiriog |
| Celert | saint's name | |
| celli | grove, copse | |
| celynnen, (plural celyn) | holly tree | Cwm-celyn |
| cemais | river bends | Cemais |
| cennin | leeks | |
| cerrig | see carreg | Cerrigceinwen |
| ceunant | ravine, gorge, brook | Ceunant Mawr |
| cewri | see cawr | |
| cil, (plural ciliau) | corner, retreat nook | Cil-y-cwm |
| cilfach | cove, creek, corner, nook | |
| cist | coffer | |
| clafdy | hospital | |
| clawdd | dyke, hedge, ditch | Penclawdd |
| clogwyn | precipice, crag | Clogwyn Melyn |
| clun | meadow, moor, brake, thicket | Clunderwen |
| clwyd | hurdle | Glanclwyd |
| clyd | sheltered | |
| Clywedog | river in | |
| cnwc | hillock, knoll | Cnwclas (Knucklas) |
| coch | red | Castell Coch |
| coed | trees, wood, forest | Betws-y-coed |
| coety | house in wood | Coety |
| cog | cuckoo | |
| collen | hazel tree | |
| com(m)ins | common | Comins-coch |
| Conwy | river in Caernarfonshire | Aberconwy |
| Corn, (plural cyrn) | horn | |
| cors | bog | |
| Cothi | river in | Dol-y-cothi |
| craig, (plural creigiau) | rock | Craig-y-nos |
| crib(in) | crest, summit, arete | |
| crin | withered | |
| croes | cross, cross-roads | Ty-croes |
| croesffordd,croeslon | cross-roads | |
| crug, (plural crugiau) | knoll, tump | |
| crwn | round | |
| Curig | saint's name | Capel Curig |
| cwm | valley, combe | Cwmtwrch |
| cwrt | court, yard | Cwrt Sart |
| Cybi | saint's name | |
| cyll | hazel trees | |
| cymer, (plural cymerau) | confluence | Cefn-coed-y-cymer |
| Cyfeiliog | river in | |
| Cynon | river in Glamorgan | Abercynon |
| cyrn | see corn |