look up any word, like eiffel tower:
 
1.
A word used in place of the word 'hilarious'.

or

A term or phrase used to signify to others the humour and 'hilairiousness' of the present moment.
Dave told me a joke, it was so halair
by Michelle Cadman and Dave Hill November 11, 2007
 
2.
A word meaning hilarious, said by people who are to lazy to say the whole word. The word originated in Wagga Wagga NSW, Australia.
that's halair.

Have you seen 21 Jump St? It was halair!
by H. Van Haren and C. Johnson June 13, 2012