The prefix means 'not'. So, for example, irresponsible means 'not responsible'.
The prefix, however, is actually in-, such as incapable. You change the n depending on the word. Words that begin with l use the prefix il- (e.g. illegal), words that begin with r use the prefix ir- (e.g. irresponsible) and words that begin with m or p use the prefix im- (e.g. immature or implausible). You use the prefix in- in all other cases.
Words with the prefix ir - :irregularirreplaceableirresponsibleirreparable
There is no prefix.
the prefix for irrigate is
The prefix "ir-" is found in irrelevant, irreverent, and irreparable.
Ir- can be a prefix for regular: irregular.
The prefix ir- is used to form the word irregular.