Breathe easy
Breathe easy/easier
Breathe one's last
Brew a plot
Bright and early
Bright-eyed and bushy-tailed
Brimming with (something)
Bring (someone or something) to its/their knees
Bring (someone) around
Bring (someone) into line
Bring (someone) to
Bring (someone) to heel
Bring (someone) to terms
Bring (something) home to (someone)
Bring (something) into question
Bring (something) off
Bring (something) on
Bring (something) to (someone's) attention
Bring (something) to a head
Bring about (something)
Bring down the house
Bring home the bacon
Bring home the importance of (something) to (someone)
Bring some new facts to light
Bring to mind
Bring up
Bring up (something)
Bring up the rear
Broad in the beam
Brown bag it
Brush up on (something)
Brush with the law
BS
BSc
Buck for (something)
Buckle down to (do something)
Budget crunch/squeeze
Bug (someone)
Bug-eyed
Build (something) to order
Build a case (against someone)
Build a fire under (someone)
Build castles in the air/in Spain
Build up (someone or something)
Build up to (something)
Bull in a china shop
Bump into (someone)
Bump off (someone)
Bundle of nerves
Burden of proof
Burn (oneself) out
Burn (someone) in effigy
Burn (something) to a crisp
Burn a hole in one's pocket
Burn down
Burn one's bridges behind one
Burn one's fingers
Burn the candle at both ends
Burn the midnight oil
Burn up
Burst at the seams
Burst in on (someone or something)
Burst into flames
Burst into tears
Burst onto the scene
Burst out laughing
Burst with joy
Burst with pride
Bury the hatchet
Bury/hide one's head in the sand
Business as usual
Busman's holiday
Bust a gut (to do something)
But for (someone or something)
Butt heads with (someone)
Butt in (on someone or something)
Butter (someone) up
Button one's lip
Buy (something) for a song
Buy (something) on credit
Buy (something) sight unseen
Buy a pig in a poke
Buy a stake in (something)
Buy off (someone)
Buy out (someone or something)
By a hair's breadth
By a long shot
By a mile
By a whisker
By a whisker/hair
By all accounts
By all appearances
By all means
By and by
By and large
By any means
By chance
By check
By fair means or foul
By far
By fits and starts
By hook or by crook
By leaps and bounds
By means of
By no means
By shank's mare
By the book
By the day
By the dozen
By the dozens
By the handful
By the hour
By the month
By the same token
By the seat of one's pants