Etymology 1 
Old English twigge, from Proto-Germanic *twīgan (compare West Frisian twiich, Dutch twijg, German Zweig), from Proto-Indo-European *dwigha (compare Old Church Slavonic dvigŭ 'branch', Albanian degë 'id.'), from *dwó 'two'. More at two.
- Rhymes: -ɪɡ
- A small thin branch of a tree or bush.
- They used twigs and leaves as a base to start the fire.
Derived terms 
Etymology 2 
From Irish and Scots Gaelic tuig, "to understand"
- (colloquial, regional) To realise something; to 'catch on'.
- He hasn't 'twigged' that we're planning a surprise party for him.
- 2012 May 30, John E. McIntyre, “A future for copy editors”, Baltimore Sun:
- Well, with fewer people doing two or three times the work, you may have already twigged to this.