The origins of the names of some settlements are unclear with different experts offering us different thoughts. Here are some . . .
| Abercrave / Abercraf | mouth of Craf stream (craf = garlic) |
| Bethlehem | the name derives from the chapel in the village |
| Brecon / Aberhonddu | derived from name of ancient lordship of Brycheiniog (itself after legendary King Brychan) / mouth of the river Honddu |
| Brynamman / Brynaman | hill by the Aman river. Formerly ‘Y Gwter Fawr’ (great channel) |
| Capel Gwynfe | holy place chapel |
| Coelbren | possibly a ‘lot’ or ‘portion’, referring to a piece of land though other origins have been suggested |
| Cray / Crai | may mean rough or severe, describing a mountain stream |
| Cwmllynfell | valley of the smooth river (cwm-llyfn-ell) |
| Defynnog | from personal name of Dyfwn? |
| Glanaman | glen of river Aman |
| Glyntawe | glen of river Tawe |
| Heol Senni | Senni road |
| Hirwaun | long meadow |
| Libanus | Latinised from of biblical Lebanon |
| Llanddeusant | church of two saints, these being Simon and Jude |
| Llandeilo | St Teilo’s church |
| Llandovery/ Llanmyddyfri | church among the waters |
| Llangadog | St Cadog’s church |
| Llanspyddid | maybe church of hawthorn tree or the personal name Ysbyddyd |
| Llwyn-on | ash grove |
| Merthyr Tydfil / Merthyr Tudful | burial place of St Tudful |
| Myddfai | meadow of round hollow |
| Penderyn | head of oak area or else bird’s head? |
| Pontneddfechan | bridge of lesser river Nedd |
| Pontsticill | bridge near a stile |
| Sennybridge / Pontsenni | bridge of R Senni (personal name) |
| Trap | step/rise in ground or a ‘trap’ of some sort? Spelling with ‘pp’ is incorrect |
| Trecastle / Trecastell | castle town |
| Ystradfellte | valley of R Mellte (mellt = lightning/swift) |
| Ystradgynlais | valley of R Cynlas (personal name or cyn-glais (= chisel stream) |