A portmanteau is a large travelling bag or suitcase with two compartments. The word comes from the Middle French porter (to carry) and manteau (mantle). In modern French the word means coat rack.
A portmanteau word or portmanteau is one that fuses several grammatical inflections, or one that combines parts of two or more words. The first definition is the one used by linguists, who know portmanteaux of the second type as blends.
The term portmanteau was coined by Lewis Carroll and first appeared in his book, Through the Looking Glass, in 1871. When explaining the word slithy from Jabberwocky, Humpty Dumpty tells Alice that “Well, slithy means lithe and slimy … You see it’s like a portmanteau — there are two meanings packed up into one word.”
Other portmanteaux in English include brunch (breakfast + lunch), smog (smoke + fog), aquarobics (aqua – aerobics), infomercial (information + comercial), advertorial (advertisement + editorial), and of course blog (web + log).
An interesting portmanteau I came across today was snickanas (snickers + bananas) – a snack one of my friends invented.
Main source: Wikipedia
I am not sure that “blog” qualifies as a portmanteau. Unlike the other words, it is not formed by combining (usually the first and last) parts of two separate words. “Weblog” is a single, compound word, from which “we-” is dropped, giving up “blog”.
The last name of my ex-boss is a portmanteau of the birthplaces of his grandparents.
What about smog? Cause it is a combination of fog and smoke.
Emma