n.
Function: intransitive verb
Etymology: probably imitative
Date: 1918
1 : BREAK DOWN especially : STALL ― usually used with out <the motor suddenly conk ed out>
2 a : FAINT b : to go to sleep ― usually used with off or out < conk ed out for a while after lunch> c : DIE <I caught pneumonia. I almost conk ed ― Truman Capote>