As in many other languages, Irish adds prefixes to words to create new words. If you become familiar with the prefixes below, you may double your vocabulary! Note that some prefixes are separated from the base word by a hyphen, and some prefixes cause lenition.

ain-   in-, un-, not-, over-
Examples: ceart (right) becomes aincheart (unjust), fios (knowledge) becomes ainfhiosracht (over-curious).

an-   very
Example: maith (good) becomes an-mhaith (very good).

ath-   re-
Example: déan (do, make) becomes athdéan (redo, remake).

ceann-   chief, main, -headed
Example: litir (letter) becomes ceannlitir (capital letter).

comh-   mutual, joint
Example: ceol (music) becomes comh-ceol (harmony).

dea-   good, well
Example: scéal (news, story) becomes dea-scéal (piece of good news).

déarg-   red-, real, utter
Example: gráin (hatred) becomes dearg-ghráin (intense hatred).

dé-   bi-, di-, two-
Example: taobh (side) becomes dethaobhach (bilateral).

di-   de-, dis-, in-, un-
Example: scéal (news, story) becomes discéil (uninformative).

do-   in-, un-, not-
Example: déanta (done, complete) becomes dodhéanta (impossible, hard to do),

il-   many, multi-
Example: eochair (key) becomes ileochair (master key).

in-   capable of
Example: creidte (believed) becomes inchreidte (believable).

lán-   total
Example: cead (permission) becomes lánchead (full permission).

réamh-   pre-, preliminary
Example: feiceáil (seeing) becomes reamhfheiceáil (foresight).

mion-   small, micro-
Example: insint (telling) becomes mioninsint (detailed report).

sár-   exceeding, ultra-
Example: riail (rule) becomes sár-riail (golden rule).

ró-   over-
Example: minic (often) becomes ro-mhinic (too often).

so-   easy
Example: briste (broken) becomes so-bhriste (fragile, easily broken).