n. 1 (context Internet neologism English) An image macro of, usually, a kitten or a cat with a humorous caption. 2 (context uncountable Internet neologism English) The deliberately misspelled and grammatically quirky form of English associated with such images' captions.
"Lolcat" is a compound word of the acronymic abbreviation for "laugh out loud" ( LOL) and the word "cat". A synonym for "lolcat" is cat macro, since the images are a type of image macro. Lolcats are commonly designed for photo sharing imageboards and other Internet forums.