1. (of rules) stringently enforced
   "hard-and-fast rules"
   - strict

See also: invariable

• boo
• boo-boo
• boob
• boob tube
• booboisie
• booby
• booby hatch
• booby prize
• booby-trap
• Boocercus eurycerus
• boodle
• boofhead
• booger
• boogeyman
• boogie
• boogie-woogie
• boohoo
• boojum
• boojum tree
• book
• book agent
• book bag
• book club
• book jacket
• book lung