- omitting
- omneities
- omneity
- omnibus
- omnifarious
- omniform
- omnipotence
- omnipotent
- omnipotents
- omnipresence
- omnipresent
- omniscient
- omnitude
- omnium gatherum
- omnivore
- omnivorous
- omnivorousness
- omophagous
- omphalic
- omphalos
- on
- on a day
- on a dime
- on a downer
- on a high horse
- on a hunch
- on a large scale
- on a leash
- on a limb
- on a line
- on a long shot
- on a par
- on a roll
- on a slant
- on a small scale
- on a sour note
- on a streak
- on a string
- on a treadmill
- on a trip
- on account
- on account of
- on accounts
- on ahead
- on alert
- on all accounts
- on all counts
- on all fours
- on an ego trip
- on an even keel
- on and off
- on and on
- on and up
- on any occasion
- on approval
- on assignment
- on assumption
- on assumption that
- on average
- on ball
- on beat
- on bed of roses
- on bed roses
- on behalf of
- on blink
- on board
- on bottom
- on brink
- on call
- on certain conditions
- on certain occasions
- on cloud nine
- on collision course
- on comeback trail
- on condition
- on counts
- on credit
- on day
- on deathbeds
- on deck
- on display
- on double
- on dry land
- on duty
- on edge
- on ego trip
- on empty stomach
- on end
- on faith
- on far side
- on fence
- on file
- on fire
- on foot
- on friendly terms
- on fritz
- on front burner
- on furlough
- on good terms
- on grounds that
- on guard
- on hand
- on hands and knees
- on head
- on high
- on high horse
- on hold
- on holds
- on holiday
- on hot seat
- on house
- on ice
- on impulse
- on internet
- on its way
- on land
- on last leg
- on layoff
- on leave
- on level
- on line
- on lookout
- on nose
- on occasion
- on occasion that
- on off
- on offer
- on on
- on one deathbeds
- on one guard
- on one occasion
- on one own time
- on one plane
- on one side
- on one's deathbed
- on one's deathbeds
- on one's game
- on one's guard
- on one's head
- on one's high horse
- on one's knees
- on one's last leg
- on one's own
- on one's own initiative
- on one's own time
- on one's side
- on one's toes
- on one's uppers
- on ones deathbeds
- on ones guard
- on other side
- on paper
- on pins and needles
- on probation
- on purpose
- on q t
- on q. t.
- on q.t.
- on qt
- on rare occasions
- on record
- on rock
- on roll
- on sabbatical
- on safe side
- on sale
- on same wavelength
- on schedule
- on second thought
- on shore
- on short notice
- on sick list
- on side
- on sidelines
- on skid
- on slippery ground
- on someone
- on speaking terms
- on spot
- on spur of moment
- on spur of the moment
- on stream
- on tap
- on target
- on tenterhooks
- on that
- on that account
- on that occasion
- on the alert
- on the and up
- on the arm
- on the assumption
- on the assumption that
- on the back of
- on the ball
- on the beam
- on the beat
- on the bench
- on the bias
- on the blink
- on the borderline
- on the bottom
- on the brain
- on the breadline
- on the brink
- on the brink of
- on the bum
- on the button
- on the canvas
- on the case
- on the comeback trail
- on the contrary
- on the critical list
- on the cuff
- on the cutting edge
- on the debit side
- on the defensive
- on the docket
- on the dole
- on the dot
- on the double
- on the east side of
- on the edge
- on the edge of
- on the face
- on the face of it
- on the far side
- on the fence
- on the fritz
- on the front burner
- on the go
- on the grounds
- on the grounds that
- on the hit list
- on the hook
- on the horizon
- on the hot seat
- on the house
- on the inside
- on the Internet
- on the job
- on the kip
- on the lam
- on the left
- on the level
- on the line
- on the lookout
- on the lookout for
- on the loose
- on the make
- on the mark
- on the mend
- on the money
- on the move
- on the nail
- on the nether side
- on the next day
- on the nose
- on the numbers
- on the occasion that
- on the order of
- on the other hand
- on the other side
- on the outs
- on the outside
- on the part of
- on the payroll
- on the point
- on the point of
- on the q t
- on the Q. T.
- on the Q.T.
- on the QT
- on the qui vive
- on the quiet
- on the rampage
- on the right track
- on the rims
- on the road
- on the road to
- on the road to recovery
- on the rock
- on the rocks
- on the ropes
- on the same wavelength
- on the scent
- on the shelf
- on the sick list
- on the side
- on the side of
- on the skid
- on the skids
- on the sly
- on the spot
- on the spur of the moment
- on the stick
- on the subject of
- on the surface
- on the tab
- on the take