1
general::
1. Unpackaged, loose, as in It's cheaper to buy rice in bulk. [Late 1600s] 2. In large amounts or volume, as in The ship was carrying wheat in bulk. [Mid-1700s]
American Heritage Idioms
2
general::
Phrase(s): in bulk
in large quantities or amounts, rather than smaller, more convenient quantities or amounts. • Jane always bought office supplies in bulk to save money. • Dave purchased cereal in bulk because his family used so much of it.
McGrawhill's American Idioms And Phrasal Verbs