mí-

From Old Irish mí-^[1] (compare Scottish Gaelic mì-), from Proto-Indo-European *mey- (“to change”). Cognate with English mis-, Latin minus (“lesser”), Ancient Greek μείων (meíōn, “less”).

mí-

1. Having a negative or missing quality

   bad, ill-, evil, dis-, mis-, mal-

2. not

   un-, in-, dis-, mis-

• Does not change form for broad or slender nouns;
• Triggers lenition when attached to a noun or adjective beginning with a consonant:

  ‎mí- + ‎ceart (“right, correct”) → ‎mícheart (“incorrect, wrong”)

  ‎mí- + ‎cothrom (“equal; balanced; level”) → ‎míchothrom (“uneven”)

• Written with a hyphen when attached to nouns or adjectives beginning with a vowel:

  ‎mí- + ‎ordú (“order”) → ‎mí-ordú (“disorder”)

• ain-
• do-
• neamh-
• ro-

• Ó Dónaill, Niall (1977) “mí-”, in Foclóir Gaeilge–Béarla, Dublin: An Gúm, →ISBN
• MacBain, Alexander, Mackay, Eneas (1911) “mí-”, in An Etymological Dictionary of the Gaelic Language‎^[1], Stirling, →ISBN

Possibly from mis (“less”). Ultimately from Proto-Indo-European *mey- (“to change”).

mí-

1. (derogatory) evil, ill, sinister

   Synonym: do-

• Irish: mí-
• Manx: mee-
• Scottish Gaelic: mì-

• Gregory Toner, Sharon Arbuthnot, Máire Ní Mhaonaigh, Marie-Luise Theuerkauf, Dagmar Wodtko, editors (2019), “mí-”, in eDIL: Electronic Dictionary of the Irish Language