HeyRua Get the app

Treacherous in Irish (fealltach): Meaning, Forms, Examples

Other uses of ‘fealltach’: deceitful · foul

The Irish for treacherous is fealltach: cara fealltach, a treacherous friend.
Updated October 2026Report a mistake

How to say “treacherous” in Irish

Irish:
fealltach
English:
treacherous, deceitful, foul
Word type:
adjective
More treacherous:
níos fealltaí
Most treacherous:
is fealltaí
Plural:
fealltacha
Pronunciation:
“FAL-tukh”  /ˈfʲal̪ˠt̪ˠəx/

What does “fealltach” mean?

“Fealltach” has three alternative meanings. The most common comes first.

treacherous
Likely to betray people who trust you.Also: traitorous, perfidious, disloyal.
2 other meanings: deceitful or foul
2deceitful
Dishonest and tricky, not to be trusted.Also: false, double-dealing, sly.
3foul
Unfair or against the rules, as in a foul blow or foul play.Also: unfair, underhand.

“Fealltach” after a noun

An Irish adjective comes after its noun. Here is fealltach after cara (friend, masculine), after bean (woman, feminine) and after a plural.

after a masculine nouncara fealltacha treacherous friend
after a feminine nounbean fhealltacha treacherous woman
after a plural nouncairde fealltachatreacherous friends

séimhiú (the h) the ending

feminine
beanwoman
+
fealltachtreacherous
=
bean fhealltacha treacherous woman

After a feminine noun the adjective gets a séimhiú, an h after its first letter: bean fhealltach. After a masculine noun it stays as it is: cara fealltach.

plural
cairdefriends
+
fealltachatreacherous, plural
=
cairde fealltachatreacherous friends

With a plural noun the adjective takes its plural form, fealltacha. It also gets an h after a plural that ends in a slender consonant; after other plurals it does not: mná fealltacha.

More treacherous, most treacherous, very treacherous

níosmore
+
fealltaítreacherous
=
níos fealltaímore treacherous
ismost
+
fealltaítreacherous
=
is fealltaímost treacherous

Bhí sé níos fealltaí ná a dheartháir. He was more treacherous than his brother.

more treacherousníos fealltaíin the past tense: ní b'fhealltaí
most treacherousis fealltaíin the past tense: ab fhealltaí
as treacherous aschomh fealltach leno change after chomh
very treacherousan-fhealltachan- lenites, except d, t and s
too treacherousrófhealltachró- lenites

“Fealltach” in a sentence: Irish examples

With a masculine noun, a feminine noun, a plural, a comparison and on its own.

Ba chara fealltach é ar deireadh.
He was a treacherous friend in the end.
Rinne sé beart fealltach orainn.
He played a treacherous trick on us.
Ní maith liom daoine fealltacha.
I don't like treacherous people.
Bhí sé níos fealltaí ná a dheartháir.
He was more treacherous than his brother.
Tá an fear sin fealltach.
That man is treacherous.

Other adjectives in Irish

More everyday Irish adjectives to learn next.

Treacherous in Irish: frequently asked questions

What is the Irish for treacherous?

The Irish for treacherous is fealltach (pronounced “FAL-tukh”). It comes after the noun: cara fealltach, a treacherous friend; bean fhealltach, a treacherous woman.

How do you say more treacherous and most treacherous in Irish?

níos fealltaí is more treacherous and is fealltaí is most treacherous. In the past tense they become ní b'fhealltaí and ab fhealltaí.

Why does fealltach become fhealltach?

After a feminine singular noun an adjective is lenited: it gets an h after its first letter. So bean fhealltach (a treacherous woman) but cara fealltach (a treacherous friend), because cara is masculine.

What is the plural of fealltach?

With a plural noun fealltach becomes fealltacha: cairde fealltacha, mná fealltacha.

How do you say very treacherous in Irish?

an-fhealltach. Too treacherous is rófhealltach, and as treacherous as is chomh fealltach le.

Does fealltach have more than one meaning?

Yes. Fealltach can mean treacherous, deceitful or foul, depending on context; the first is the most common.

What noun is related to 'fealltach'?

The noun is 'feall' (treachery, betrayal), as in 'feall a dhéanamh ar dhuine', to betray someone. A traitor is 'fealltóir'.

Learn Irish by
actually speaking it

Learn everyday Irish words like fealltach through guided conversation with Rua.

7-day free trial. Cancel anytime.

The HeyRua app home screen