- Nail your colours to the mast
- Namby-pamby
- Name and shame
- Name is mud
- Nasty, brutish and short
- Nation of shopkeepers
- Nature versus nurture
- Nautical phrases
- Near the knuckle
- Necessity is the mother of invention
- Ne'er cast a clout till May be out
- Ne'er do well
- Needs must
- Neither a borrower nor a lender be
- Neither fish nor flesh, nor good red herring
- Neither here nor there
- Nest-egg
- Nest of vipers
- Never give a sucker an even break
- Never knowingly undersold
- Never look a gift horse in the mouth
- Never-never land
- Never the twain shall meet
- Nevertheless
- New kid on the block
- Nice as ninepence
- Nice kettle of fish
- Nicholas Udall
- nick of time
- Night owl
- Nine days' wonder
- Nip and tuck
- Nip in the bud
- Nitty-gritty
- No-brainer
- No dice
- No holds barred
- No laughing matter
- No love lost
- No man is an island
- No more cakes and ale?
- No names: no pack-drill
- No quarter given
- No rest for the wicked
- No room to swing a cat
- No truck with
- No way, Jose
- Nod is as good as a wink
- Nod
- Norange
- Nosy parker
- Not a dicky-bird
- Not by a long chalk
- Not by a long shot
- Not my cup of tea
- Not for all the tea in China
- Not playing with a full deck
- Not rocket science
- Not tonight Josephine
- Not worth a plugged nickel
- Not worth the candle
- Nothing is certain but death and taxes
- Nothing succeeds like success
- Noughts and crosses
- Nothing ventured, nothing gained
- Now is the winter of our discontent
- Nth degree
- Nul points
- Nutshell