ym-

ym-

1. circum-, peri-, around

Ultimately from Proto-Indo-European *h₂m̥bʰi (“round about, around”). Cognate with Cornish om-, Latin amb- (“around, about”), ambi- (“both”), English um-, umb- (“around, about”), Ancient Greek ἀμφί (amphí, “around, about”).^[1]

• IPA^(key): /əm/

ym-

1. self, reflexive prefix

   ‎ym- + ‎golchi (“wash”) → ‎ymolchi (“wash oneself, have a wash”)

   ‎ym- + ‎uno (“to unite”) → ‎ymuno (“to join”)

   ‎ym- + ‎diswyddo (“dismiss, discharge”) → ‎ymddiswyddo (“resign”)

2. each other, mutual, reciprocal prefix

   ‎ym- + ‎gweld (“to see”) → ‎ymweld (“to visit”)

   ‎ym- + ‎lladd (“to kill”) → ‎ymladd (“to fight”)

   ‎ym- + ‎holi (“ask”) → ‎ymholi (“to inquire”)

In many words, the original reflexive or reciprocal force of this prefix has now been lost and the relationship between the root and derived words is not always apparent, e.g. ymosod (“to attack”) from gosod (“to put, to place”), ymollwng (“to succumb, to flop”) from gollwng (“to leak, to drop”).

• R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “ym-”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies