What is a portmanteau word, or a portmanteau? A one-sentence definition is easy enough: a portmanteau word is, in summary, a word that has been formed by blending two existing words together. So, for instance, a motel is from motor + hotel, brunch is from ­breakfast + lunch, and smog is from smoke + fog. But there are some curious aspects of portmanteau words – not least that term’s origin – which are worth delving into.

The term ‘portmanteau word’ has its origins in one of the best-loved works of children’s literature, Through the Looking-Glass by Lewis Carroll, published in 1871. In that sequel to Alice’s Adventures in Wonderland, Carroll includes a poem, ‘Jabberwocky’, which begins:

’Twas brillig, and the slithy toves
Did gyre and gimble in the wabe:
All mimsy were the borogoves,
And the mome raths outgrabe.

You can read the rest of ‘Jabberwocky’, and learn more about it, here. The key thing that interests us here is Carroll’s use of (invented) words in this opening stanza of the poem. What are ‘toves’, and why are they ‘slithy’? What does ‘slithiness’ (is that a word?) look or feel like? The same with ‘mimsy’. Noam Chomsky’s ground-breaking work in linguistics surrounding children’s ability to acquire a linguistic ‘grammar’ demonstrated that even if we don’t know the meaning of a word, we can often deduce what kind of word it is: i.e. we know ‘mimsy’ is an adjective, or describing-word, even though we don’t fully know what ‘mimsiness’ is.

Carroll is using both ‘slithy’ and ‘mimsy’ as portmanteau words: slithy, for example, is a blend of slimy + lithe, while mimsy suggests miserable + flimsy. Another term for a portmanteau word is, in fact, a blend, and some linguists prefer to use the word blend. But the term ‘portmanteau’ came about because, after Alice has encountered the poem ‘Jabberwocky’ in Through the Looking-Glass, and puzzled over the meaning of these unfamiliar words, she meets Humpty Dumpty, who tells her, when she quotes the above stanza:

‘That’s enough to begin with,’ Humpty Dumpty interrupted: ‘there are plenty of hard words there. “Brillig” means four o’clock in the afternoon — the time when you begin broiling things for dinner.’

‘That’ll do very well,’ said Alice: ‘and “slithy”?’

‘Well, “slithy” means “lithe and slimy”. “Lithe” is the same as “active”. You see it’s like a portmanteau — there are two meanings packed up into one word.’

A portmanteau was, in Victorian times, a case or bag for carrying clothing while travelling; the word is from the French meaning literally ‘carry the cloak’.

Curiously, both slithy and mimsy had independent lives separate from Lewis Carroll’s use of them: William Whately had used ‘slithy’ (as a variant of ‘sleathy’, meaning slovenly or careless) in 1622, while mimsy, with a slightly different meaning (‘prim; affected; feeble; lightweight’), is recorded from 1880, but appears to have been coined independently of Carroll’s novel. (This sense of mimsy, as opposed to Carroll’s which refers to unhappiness, is the more common way in which the adjective is used.) However, two coinages from subsequent stanzas in ‘Jabberwocky’ would go on to become household words: chortle (from chuckle + snort) and galumph (gallop + triumph), both used to describe the actions of the titular Jabberwock, are now in common use.

A good number of portmanteau words are, fittingly enough, words which are used to describe hybrid animals or crossbreeds: so a cockapoo (cocker spaniel + poodle) is a crossbreed of those two breeds of dog, while a liger (lion + tiger) is the offspring of a male lion and a female tiger. (Similarly, a tigon, from tiger + lion, is the offspring of a lioness and a male tiger.) So a portmanteau word is a handy construction for describing two things which have been joined together in some way. Portmanteau words, as a branch of word-formation, are relatively recent: all of the examples given in this introduction to the form date from the mid-nineteenth century or later. Lewis Carroll wasn’t late to the party in defining or naming the portmanteau word: he arrived just in time.

Some words are portmanteaus but their origins as portmanteaus aren’t as obvious. For example, the word meld, meaning to merge two things together, is an example of a portmanteau word: it’s from the words melt + weld. (There is a separate and rarer word, ‘meld’, which is used in card games and means to announce one’s hand or one’s bet; but that word is derived from the German melden, meaning ‘announce’.) And it’s easy to forget that Wi-Fi (Wireless + Fidelity), breathalyser (breath + analyser), and podcast (actually from the brand name iPod + broadcast) are all examples of portmanteau words.

It’s worth, by way of conclusion, contrasting the portmanteau word or blend with another type of word-formation: the compound word. A compound is where two words are placed together, e.g. house + boat = houseboat, or dog + food = dogfood. In a portmanteau word, there is always some abbreviation of one or both of the words involved: so smog takes the first two letters of smoke and the last two letters of fog but ditches the rest. Even in cockerpoo, the term spaniel is lost from the first term, cocker spaniel. A portmanteau word packed two meanings up into its carry-case, but some letters are always jettisoned.