(See also CORRECTNESS.)

bang on Exactly on; directly on; precisely as planned; apt or appropriate. This British slang phrase often appears as bang on target, popularized by bomber lingo during World War I.

By extension, the phrase also describes anything which is just right, apt, or appropriate.

Spot on is another British slang phrase which is used interchangeably with bang on.

dot one’s i’s and cross one’s t’s To be precise or meticulous down to the last or smallest detail; to particularize in detail so as to leave no room for doubt or uncertainty; to cite chapter and verse. This expression is said to have sprung from the possibility of confusing i’s with t’s if they are carelessly written without the respective dot and cross. The phrase has been in figurative use since the 1800s.

hit the nail on the head To do or say the most fitting thing; to cut through extraneous details and come right to the point; to make a clear, pithy statement. This expression has been in print since the 16th century. Hitting a nail properly—that is, squarely on the head —is likened to communicating effectively, or to the point. On the other hand, a bad hit which bends the nail is like rambling which fails to get to the crux of a matter.

Occam’s razor The maxim that unnecessary facts or assumptions used to explain a subject must be eliminated. William of Occam, the 14th-century English scholastic philosopher known as “the Invincible Doctor,” believed that general ideas have no objective reality outside the mind (nominalism). Razor in this expression is a metaphorical term for the precise, dissecting, incisive methods which characterize Occam’s intellectual approach.

on the button Exactly, precisely; punctually, promptly; on the dot; often right on the button. This expression derives from the boxing slang use of button to mean the point of the chin. Literally then, on the button indicates a perfectly aimed punch to the chin or jaw area intended to knock a fighter out or at least seriously impair his ability to retaliate.

on the money At precisely the right time or place, right on target; often right on the money. This American slang expression appears to refer to money placed as a bet against a certain, previously stated outcome.

on the nose Precisely; right on target; on time. On the nose is old radio parlance describing the producer’s gesture of putting his finger on his nose to signify that the program was running according to schedule. The phrase is now used especially in regard to time but can describe anything which is accurate, precise, or apt. On the button is akin to on the nose in meaning and usage, and both are American equivalents of the British phrases bang on and spot on.

to a T Exactly, precisely, perfectly.

The OED dismisses as untenable the popular belief that this expression is an allusion to the T square, a draftsman’s T-shaped ruler for the accurate drawing of right angles, parallel lines, etc. It conjectures instead that it was the initial of a word, perhaps tittle ‘dot, jot,’ since this was in use nearly a century before to a T in exactly the same constructions. Use of the expression dates from at least the late 17th century.