(sports) A tap on the groin given from one (male) athlete to another, to check if the other is wearing a cup by hitting them lightly in the testicles.

The act of checking that something does not contain elementary mistakes or impossibilities, or is not based on invalid assumptions.

A check or review to make sure something is consistent, reasonable, etc. / (idiomatic) A wake-up call, reminder.

(intransitive) To confirm and pay for goods and services at a facility (e.g.: supermarket, online store, hotel) when leaving.

(US) A service provided at certain businesses which allows one to check one's coat for safekeeping while inside.

An extra check or verification made a second time, usually with additional caution or attention. / (chess, uncountable) A check delivered by two pieces simultaneously.

To check again; to check with extra caution or attention; to verify or make sure.

(Canada, US) An instance of looking backwards over one's shoulder while driving or biking, before changing lanes or making a turn, to see if any vehicles are in one's blind spots.

(intransitive, Canada, US) To look backwards over one's shoulder while driving or biking, before changing lanes or making a turn, to see if any vehicles are in one's blind spots.

(idiomatic) A cursory inspection or examination or the inspection or examination of a sample of something.