Knick-knack and bric-a-brac?

Solution 1:

They are called reduplications:

• The coinage of new words and phrases into English has been greatly enhanced by the pleasure we get from playing with words. There are numerous alliterative and rhyming idioms, which are a significant feature of the language. These aren't restricted to poets and Cockneys; everyone uses them. We start in the nursery with choo-choos, move on in adult life to hanky-panky and end up in the nursing home having a sing-song.

• The repeating of parts of words to make new forms is called reduplication. There are various categories of this: rhyming, exact and ablaut (vowel substitution).

  • Examples, are respectively, okey-dokey, wee-wee and zig-zag. The impetus for the coining of these seems to be nothing more than the enjoyment of wordplay. The words that make up these reduplicated idioms often have little meaning in themselves and only appear as part of a pair. In other cases, one word will allude to some existing meaning and the other half of the pair is added for effect or emphasis.

Origin of knick-knack:

• Knick doesn't mean anything in itself in this term; it is merely a reduplication of knack. We now use knack as meaning 'a dexterous facility', but in the 16th century it was used to mean 'an ingenious contrivance; a toy or trinket', and that's the sense that was used in knick-knack.term;

• Shakespeare also used it in The Taming of the Shrew, 1596:

  • "Why 'tis a cockle or a walnut-shell, A knacke, a toy, a tricke, a babies cap: Away with it."

• When knick-knack was first used it meant 'a petty trick or subtefuge'. John Fletcher, used it that was in his work The loyall subject, 1618:

  • "If you use these knick-knacks, This fast and loose. "

• By 1682, that meaning had died out though and a translation of Nicolas Boileau-Despréaux's Le Lutrin was using the term with the meaning we currently have for it, that is, small trincket:

  • "Miss won't come in to Buy, before She spies the Knick-knacks at the Dore".

(The Phrase Finder)