The definite article is the word ‘the’ in English. In Welsh it is one of three: y (before a consonant), yr before a vowel, ‘r after a vowel regardless of what follows.

The ‘yes and no’ options:

The Welsh name for the UK contains the article: y Deyrnas Unedig, but the Welsh names Cymru (Wales), Lloegr (England), and Gogledd Iwerddon (Northern Ireland) do not. Yr Alban (Scotland) does, so it’s green.

Tsiecia (Czechia) does not have the article but y Weriniaeth Tsiec (the Czech Republic) does.

Gwlad Groeg (Greece) does not have the article, but y Weriniaeth Helenaidd (the Hellenic Republic) does.

For the green countries, the names are: Gwlad yr Iâ (Iceland); Y Ffindir (Finland); Yr Almaen (Germany); Yr Iseldiroedd (The Netherlands); Y Swistir (Switzerland); and Yr Eidal (Italy). Iwerddon (Ireland) technically does: the initial ‘I’ is from the article and its older name was Y Werddon but this is no longer perceived.