"Tethydan" is a Welsh word spelled in a way that reflects the phonology of the language. The first syllable "Teth" is pronounced with a "th" sound, as in "thought," while the "y" in the second syllable represents the Welsh sound "ə" (schwa), similar to the "u" in "but." The final syllable is pronounced with a long "a" sound followed by a nasalized "n." The IPA transcription of "Tethydan" is /ˈteθɪdan/.