English has conquered the world, via America, but it has always been open to borrowing from other languages. Conquerors tend to lay down the rules of what is spoken, which is how we acquired a good many French words from the 11th century on, while very few Welsh words have made their way into English. Cwm, for valley, is one, and eisteddfod, of course (it's interesting to come across this in another culture - a music festival in South Africa is an eisteddfod) which is related to the Welsh word for sit; an honoured bard would receive a place at the lord's table. Can anyone add to this short list?
The French, meanwhile, borrow reluctantly from us, especially words to do with leisure - football and weekend are two - while we seem to allow traffic in the opposite direction rather more enthusiastically. Wasn't it Norman Lamont who announced (in a typical Brit-French accent) "Je ne regrette rien," quoting Edith Piaf's famous chanson as he left office? Chanson we've adopted (to mean a particular kind of French folk song) with aplomb. Food we accept as being full of French words: baby marrows soon became courgettes and we are quite at home with aubergines, despite the fact that Americans still prefer to say egg-plants. Everyone understands dej... vu, for which we have no Anglo-Saxon equivalent, and the word tranche has quite recently been taken up by politicians who might once have talked about slicing a cake of resources.
And as for en suite (pronounced on sweet) - no self-respecting British hotelier would offer a room which wasn't - regardless of the fact that the room by itself can't logically be any such thing; the literal meaning is "in sequence".