The word 'teeny-weeny' is a classic example of reduplication, a playful linguistic process used to create emphasis or a childlike, affectionate tone. It is formed by taking the word 'tiny' (itself from Middle English 'tine', meaning small) and altering it to 'teeny', then adding a rhyming, nonsensical counterpart 'weeny', likely influenced by the Scots word 'wee'. This pattern is common in English nursery language and colloquialisms, where sound symbolism and repetition are used to intensify meaning or convey endearment. The term's logic lies not in classical roots but in phonetic play, evolving directly within English to humorously denote something very small.

This is a reduplicative compound. 'Teeny' is a variant of 'tiny', and 'weeny' is a rhyming, playful alteration of 'tiny' or 'wee'. Both elements function together as a single, expressive unit.