Daily use of Irish in the Republic falls 1.7%
Fewer than one in 50 people speaks Irish on a daily basis in the Republic, the Census found.
Dublin's Central Statistics Office (CSO) said that just over 1.7 million people, or 39.8% of the population, said they were able to speak the language, down slightly (0.7%) on 2011.
More women than men have Irish - 968,777 compared with 792,643.
But while four in 10 of the population claim to be able to speak Irish, few do so on a daily basis, and the number is falling.
The total number speaking Irish on a daily basis stood at 73,803, representing 1.7% of the population, a drop of 3,382 compared with 2011.
The data also shows more women (40,361) than men (33,442) converse in Irish every day.
There were just 631 male daily speakers aged 35-44, compared with some 1,000 women.
The highest county-wide percentage of speakers across both sexes is in Galway, at 49%.