Definition of "Bulk" :

noun: the property possessed by a large mass

noun: the property of something that is great in magnitude

"It is cheaper to buy it in bulk."

noun: the property resulting from being or relating to the greater in number of two parts; the main part

"The bulk of the work is finished."

verb: cause to bulge or swell outwards

verb: stick out or up

"The parcel bulked in the sack."