Summit, top. Written Mullagh, Mullach, Mull — the same Irish word, mullach, in the spellings English gave it.
Mullach is a summit, a top — the top of a hill rather than the hill itself. Mullaghmore is the big summit; Mullingar is Muileann gCearr, a different word entirely (the left-handed mill), and a warning that the decoder's guesses need the Irish form to be sure.
Source: P. W. Joyce, The Origin and History of Irish Names of Places (1869–1913) · Logainm ↗
Summit, top: it is the Irish mullach. Mullach is a summit, a top — the top of a hill rather than the hill itself. Mullaghmore is the big summit; Mullingar is Muileann gCearr, a different word entirely (the left-handed mill), and a warning that the decoder's guesses need the Irish form to be sure.
mullach. English spellings of the same word include Mullagh, Mullach, Mull, because the names were written down by ear.
Mullingar (An Muileann gCearr).