(US, vulgar, chiefly in the negative) To have the most basic level of intelligence or common sense.

(chiefly US, in negative constructions) To know something, even if only a little, about. / (chiefly US, idiomatic) To know nothing, or almost nothing, about.

A sheet metal worker, especially one who works with HVAC ductwork.

plural of knock-on effect

(idiomatic) To have no common sense; to be ignorant of the most basic facts; to be very confused.

(idiomatic) To know or recognise someone at all.

(colloquial, childish) A retort to a negative accusation, implying that the accuser shares the fault.

A knot similar to the reef knot but crossed the opposite way.

(idiomatic) To know all there is to be known about a certain discipline.

(ditransitive) To inform (someone) (of something).