General meaning: "not" or "the opposite of"
* irrelevant: not relevant
* irregular: not regular
* irresponsible: not responsible
* irreplaceable: cannot be replaced
* irreversible: cannot be reversed
* irresistible: impossible to resist
* irrespective: without regard to
* irresponsible: not responsible
* irate: angry
* ironic: unexpected and often amusing
* irrational: not logical
* irrespective: without regard to
* irreducible: cannot be made smaller
* irreconcilable: cannot be reconciled
Other examples:
* irradiate: to expose to radiation
* irritate: to annoy
* irrigate: to supply water to land
* irrupt: to burst in suddenly
* irrigate: to supply land with water
Note: The prefix "ir-" is usually used before words beginning with "r," but sometimes it can also be used before other consonants, especially "l."