The Proto-Turkic word *bẹĺ(k)
Word *bẹĺ(k)
Meaning five

Comments
S. A. Starostin, A. V. Dybo, O. A. Mudrak - An Etymological Dictionary of Altaic Languages, 2003, Brill

Other words that might be of interest
*bir ‘one’, *e̟k(k)i ‘two’, *otuŕ ‘thirty’, *üč, öč ‘three’, *dö̅rt ‘four’, *altɨ ‘six’, *jẹt(t)i ‘seven’, *sekiŕ ‘eight’, *tokuŕ ‘nine’