Since I posted them i a thread on the irish part of the forum, here are some time expressions in Scottish Gaelic (Gàidhlig).

Months in Gaidhlig [genitive in brackets]

1. Am Faoilteach (masc) [an Fhaoiltich] – Variants: Am Faoilleach [an Fhaoillich]; Mios Marbh; Deireadh-Geamhraidh
2. An Gearran (masc) [a' Ghearrain]
3. Am Mart (masc) [a' Mhairt]
4. An Giblean (masc) [a' Ghiblein]
5. An Ceitean (masc) [a' Cheitein] – Variant: A' Mhaigh (fem) [na Maighe]
6. An t-Ogmhios (masc) [an Ogmhiosa] – Variant: Meadhan-Samhraidh
7. An t-luchar (masc) [an luchair] – Variants: Deireadh-Samhraidh; Mios Buidhe
8. An Lunasdal (masc) [an Lunasdail]
9. An t-Sultain (fem) [na Sultaine]
10. An Damhair (fem) [na Damhair]
11. An t-Samhain (fem) [na Samhna]
12. An Dubhlachd (fem) [na Dubhlachd] – Variant: Mios na Nollaige

March 1st – A' chiad latha dhen Mhart
June 24th – An ceathramh latha air fhichead dhen Oigmhios
September 31st – A' chiad latha deug air fhichead dhen t-Sultain
December 22nd – An darna latha air fhichead dhen Dubhlachd

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I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.

And here are the names of major holidays in Gàidhlig.

New Year's Day – Là na Bliadhna Ùire
Epiphany – Là Féill nan Rìgh
Candlemas – Là Fhéill Brìghde nan Coinnlean
St. Bridget's Day – [“Day of cock-fighting] Là Cath Choileach
Purification Day – Là Fhéill Muire nan Coinnlean
St. David's Day – Là Dhaibhidh
Easter Day – Là Càisge
Lady Day – Là Muire, Là na Caillich
May Day – Là Bealltainn
Day of the Holy Cross – Là na Crois Naoimhe
Restoration Day – Là Aisig Rìgh Theàrlaich a Dhà
St. John's Day (24 June) – Là Fhéill Eòin Baiste
Lammas-Day – Là Lùnast
Mary's Nativity – Là Breith Muire
Martinmas – Là Fhéll Màrtainn
Michaelmas – Là Fheill Mìcheil
All-Hallows Day / All-Saints Day – Là nan Uile Naomhe / Là Mairbh na Cruinne gu Coitchionn
November 1st – Là Sàmhna / An t-Samhainn
Christmas Day – Là Nollaig
St. John's Day – Là Fhéill Eòin
St. Patrick’s Day – Là Fheill Pàdraig Earraich
Also: Là nan Trì Sealladh ["Day of the three sights"], because on St. Patrick’s Day in spring, three sights may be seen (plowing, sowing and harrowing). Some versions mention seven sights.
St. Patrick's day is also called Là nan Seachd Oibrichean fichead (“Day of the twenty-seven works”), meaning that twenty-seven different kinds of work are done on a farm on that day.

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I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.