Notes
The standard reference book, A Gazetteer of Welsh Place-Names (University of Wales Press, 1967) uses tyn (without an apostrophe) for the contracted form of the Welsh noun tyddyn (homestead or smallholding).
The hyphen is used in Welsh place-names in order to aid pronunciation by showing that stress does not fall on the penultimate syllable. The stress falls on the final syllable of this name and therefore the final syllable is preceded by a hyphen.
