3. Support or aid given to a person or cause.
4. (Bookbinding)
Defn: The preparation of the back of a book with glue, etc., before putting on the cover.
BACKJOINT
Back"joint`, n. Etym: [Back , a. or adv. + joint.] (Arch.)
Defn: A rebate or chase in masonry left to receive a permanent slab or other filling.
BACKLASH
Back"lash`, n. Etym: [Back , adv. + lash.] (Mech.)
Defn: The distance through which one part of connected machinery, as a wheel, piston, or screw, can be moved without moving the connected parts, resulting from looseness in fitting or from wear; also, the jarring or reflex motion caused in badly fitting machinery by irregularities in velocity or a reverse of motion.
BACKLESS
Back"less, a.
Defn: Without a back.
BACKLOG
Back"log`, n. Etym: [Back, a. + log.]