twll yn ei gosyn

== Welsh == === Etymology === Literally, “a hole in one's cheese”. === Noun === twll yn ei gosyn (f …yn ei chosyn) (idiomatic) disappointment â thwll yn ei gosyn. ― disappointed === Further reading === D. G. Lewis, N. Lewis, editors (2005–present), “cosyn”, in Gweiadur: the Welsh–English Dictionary, Gwerin R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke, et al., editors (1950–present), “twll yn ei gosyn”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies