under lock and key

: in or into a position below or beneath something

: below or short of some quantity, level, or limit

: in or into a condition of subjection, subordination, or unconsciousness

: below or beneath so as to be overhung, surmounted, covered, protected, or concealed by

: subject to the authority, control, guidance, or instruction of

: receiving or undergoing the action or effect of

: lying or placed below, beneath, or on the ventral side

: facing or protruding downward

: lower in rank or authority : subordinate

: a tuft, tress, or ringlet of hair

: the hair of the head

: a cohering bunch (as of wool, cotton, or flax) : tuft

: a fastening (as for a door) operated by a key or a combination

: the mechanism for exploding the charge or cartridge of a firearm

: an enclosure (as in a canal) with gates at each end used in raising or lowering boats as they pass from level to level

: to fasten the lock of

: to make fast with or as if with a lock

: to fasten in or out or to make secure or inaccessible by or as if by means of locks

: a usually metal instrument by which the bolt of a lock is turned

: any of various devices having the form or function of such a key

: a means of gaining or preventing entrance, possession, or control

: extremely or crucially important

: to lock or secure with or as if with a key : fasten: such as

: to secure (something, as a pulley on a shaft) by a key

: to finish off (an arch) by inserting a keystone

: a low island or reef

: a kilogram especially of marijuana or heroin