Part-of-Speech tagging (POS tagging) is the grammatical analysis of every word that is in an phrase or sentence. Every word is labelled according to the word class it belongs to (e.g. noun, adjective, verb, pronoun etc.) along with its grammatical form (i.e. person, number, gender, tense, modus, case).

Example of Part-of-Speech Tagging: “Tá mé sásta.”
verb, present tense
pronoun, 1 person, singular

This is an important part in any speech synthesis system, because the pronunciation of a word sometimes depends on the the word class it belongs to. Take, for example, the spelling of
‘d e i r e a d h’. The word is pronounced in two different ways, depending on its meaning: Ag deireadh an lae (noun) and deireadh sé i gcónaí (verb, past habitual). The synthesiser uses the information provided by the POS tagger to determine the right pronunciation. Listen to an example.

A POS tagger for Irish has been developed by Dr Elaine Uí Dhonnchadha, Trinity College Dublin. You can try it here.