dipstick

noun

1. A stick or rod used to measure the depth of a liquid. Often used to check the level at which a liquid in an opaque or inaccessible tank or reservoir stands; gauge.

   “I haven't checked the oil level of my car's motor since I lost the dipstick three months ago.”

2. (derogatory, obsolete)An exciseman or supervisor who measures with a dipstick.
3. (slang)The penis.
4. (derogatory, slang)A useless person of inferior intellect; a dipshit.

   “That referee is a right dipstick.”

verb

1. (transitive)To check (a person) for their understanding of something, as of a lesson, or attitude toward something.

   “What most educators mean by “doing Madeline Hunter” is using her seven-step approach to planning a lesson. In Santa Barbara, as in most of her road shows, several hours are devoted to spelling out this technique, which calls for specific acts of review, introduction, explanation, “modeling” (demonstrating), “dipsticking” (checking for understanding), “monitored practice” and independent study.”

   “In private, Secretary Powell, an amateur automotive mechanic, complains that old friends spend too much time sympathetically taking his temperature — “dip-sticking me,” as he puts it.”

2. (transitive)To measure the level of a fluid using a dipstick.

   “If one of the fuel gauges is inoperative (flight is not permitted if both have failed), the tanks have to be dipsticked before and after each fueling to confirm the aircraft's fuel status.”