Merriam-Webster Collegiate Dictionary - lock

 I. noun  Etymology: Middle English lok, from Old English locc; akin to Old High German loc ~, Greek lygos withe, Latin luxus dislocated  Date: before 12th century  1.  a. a tuft, tress, or ringlet of hair  b. plural the hair of the head  2. a cohering bunch (as of wool, cotton, or flax) ; tuft  3. plural dread~ 2  II. noun  Etymology: Middle English lok, from Old English loc; akin to Old High German loh enclosure and perhaps to Old English locc ~ of hair  Date: before 12th century  1.  a. a fastening (as for a door) operated by a key or a combination  b. the mechanism for exploding the charge or cartridge of a firearm  2.  a. an enclosure (as in a canal) with gates at each end used in raising or lowering boats as they pass from level to level  b. air ~  3.  a. a ~ing or fastening together  b. an intricate mass of objects impeding each other (as in a traffic jam)  c. a hold in wrestling secured on one part of the body; broadly a controlling hold his paper…had a ~ on a large part of the state — John Corry  4. one that is assured of success or favorable outcome  III. verb  Date: 14th century  transitive verb  1.  a. to fasten the ~ of  b. to make fast with or as if with a ~ ~ up the house  2.  a. to fasten in or out or to make secure or inaccessible by or as if by means of ~s ~ed himself away from the curious world ~ed her husband out  b. to fix in a particular situation or method of operation a team firmly ~ed in last place  3.  a. to make fast, motionless, or inflexible especially by the interlacing or inter~ing of parts ~ wheels ~ a knee  b. to hold in a close embrace  c. to grapple in combat; also to bind closely administration and students were ~ed in conflict  4. to invest (capital) without assurance of easy convertibility into money  5. to move or permit to pass (as a ship) by raising or lowering in a ~  intransitive verb  1.  a. to become ~ed  b. to be capable of being ~ed  2. interlace, inter~  3. to go or pass by means of a ~ (as in a canal)  • ~able adjective