According to notes reproduced in volume XII of The History of Middle-earth, Tûk was thought by the Tooks themselves to come from an old word tūca, meaning 'daring', though Tolkien calls this 'a wholly unfounded guess' on their part. The name 'Took', of course, also exists as real modern surname, also of uncertain meaning (though some sources suggest a circuitous derivation from Thor kil, 'Thor's kettle').

Thain Gerontius (otherwise known as the Old Took) had a total of twelve children. For clarity, this selective family tree only includes those who played a part in the descent of the Thainship, or whose descendants were important in the history of the Third Age. The omitted children were (in order of age) Hildigard, Isembold, Hildifons, Isembard, Donnamira and Isengar.