These days, we may launch many things, from a boat to a spacecraft, a business project or a book, or we might say that a child launched a toy at another one! So it is indeed a useful word.
Its story in English begins around 1300. It came from Old French, a dialectal variation on lancier from Northern French; lancher. This meant “fling, hurl”. As it came into English, it started to further take on the meaning of “leap” in addition to the notion of “throw”. Take a look at these examples from Middle English, from a similar timeframe:
Firstly, the word appears meaning “throw” in the Prose Merlin, which was translated from French in the middle of the fifteenth century;
I saugh hem launche at hym knyves and gavelokkes and dartes soche foison as it hadde reyned from heuene.
(I saw him launch/hurl knives and iron bars and darts at him as though it were raining from heaven)
And then there is this example, where it means “jump” or “leap” from the Promptorium Parvulorum, which was completed in about 1440.
Lawnchyn, or skyppyn ouer a dyke, or oþer thyngys lyke
(Leaping or skipping over a ditch or over things like that).
Obviously, at that time, the spelling of the word was by no means fixed, and the variations may reflect the writer’s personal preference or pronunciation. This is subject to debate, however, as the same author has been known to use a variety of spellings for the same word!
Getting back to our word, we find that the French form lancier came from Late Latin lanceare, which meant “use a lance”. Unsurprisingly, this came itself from Latin lancea, which meant “spear”. This also means, of course, that ‘launch’ is a cognate of ‘lance’.