An Etymological Dictionary of Astronomy and Astrophysics

1. A small dot, mark, check, or electronic signal, as used to mark off an item on a list, serve as a reminder, or call attention to something (Dictionary.com).
   

2. To mark with a tick or ticks (usually followed by off).

Etymology (EN): M.E. tek “little touch,” akin to Du. tik “a touch, pat,”
M.H.G. zic.

Etymology (PE): Sof, sofidan, related to sufâr “the groove at the end part of an arrow,” → nock, on the model of Fr. coche “notch, score.”