n. & v.
n. 1 a slight error; a slip of memory etc. 2 a weak or careless decline into an inferior state. 3 (foll. by of) an interval or passage of time (after a lapse of three years). 4 Law the termination of a right or privilege through disuse or failure to follow appropriate procedures.
v.intr. 1 fail to maintain a position or standard. 2 (foll. by into) fall back into an inferior or previous state. 3 (of a right or privilege etc.) become invalid because it is not used or claimed or renewed. 4 (as lapsed adj.) (of a person or thing) that has lapsed. lapse rate Meteorol. the rate at which the temperature falls with increasing altitude. lapser n.
[ L lapsus f. labi laps- glide, slip, fall ]