‘Afon’ is of course the common Welsh word for river whilst ‘nant’ is a stream though it can also mean valley. ‘Aber’ refers to the mouth of a river or the entry of a smaller river into a larger one. ‘Cymer’ is confluence; the meeting of two rivers.
| Afon Aman | ‘Aman’ is either a personal name or comes from ‘amanw’ meaning pig/let. The river gives its name to Ammanford/Rhydaman, Glanaman and to Brynaman |
| Afon Bran | ‘bran’ is crow and may be a reference to the colour of the water – peaty or perhaps shaded? |
| Afon Cennen | ‘cennen’ is leek or lichen or possibly a personal name ‘Cennen’ |
| Afon Clydach | A common river/stream name in South Wales – ‘clydach’ means sheltered, strong, swift or stony. |
| Afon Crai | ‘crai’ may mean rough or severe. The river gives its name to the village too. |
| Afon Cynrig | meaning not known |
| Afon Gwydderig | meaning not known |
| Afon Hepste | ‘dry river’ perhaps? |
| Afon Hydfer | ‘bold stream’ |
| Afon Llia | meaning not known |
| Afon Mellte | lightning river – perhaps due to its rising & falling quickly, or else its jagged course. Gives its name to the village of Ystradfellte. |
| Afon Nedd Fechan | little Neath river. The meaning of ‘nedd’ is not known but is probably related to the R. Nidd in N. Yorkshire |
| Afon Pyrddin | ‘pyrddin’ is the ‘pure man’ – an allusion to St David |
| Afon Sawdde | meaning not known |
| Afon Senni | ‘Senni’ is either a personal name or means ‘insulting’ – referring perhaps to the sound of its flow? |
| Afon Tarell | meaning not known |
| Afon Taf Afon Tawe / River Tawe | ‘taf’ is an old name with similar origins to the name ‘tawe’ ‘tawe’ is an old name possibly signifying still and deep flowing. |
| Afon Twrch | ‘boar river’ – from supposed ‘snouting’ action of its waters or perhaps ‘burrowing’ through the land? |
| Afon Tywi / River Towy | ‘tywi’ probably signifies still and deep flowing |
| Afon Wysg / River Usk | Either from British word ‘isca’ meaning water (the rivers Axe, Exe and Esk have the same origin) or meaning ‘abounding in fish’. |
| Sychryd | ‘sych’ means dry |
| Taf Fawr | big Taf – see Afon Taf |
| Taf Fechan | little Taf – see Afon Taf |