These words refer to size or amounts that are exceedingly small. Minute describes something so small as to be seen with difficulty, and it can refer to both size and amount: a jade carving that teems with minute representations of plants and animals; a minute trace of poison discovered during a post-mortem. The word may emphasize that something is small to the point of having no significance or value; it may also indicate something so small as to require careful scrutiny if it is to be understood: a minute amount of radioactivity that could hurt no one; a minute crack in the wall that led to the amazing discovery. Minute has a related use referring to the intensive scrutiny itself: a minute examination of the murder weapon.

Minuscule is derived from a word referring to an early script that used lower-case letters. While the word can still refer literally to such a script, more generally it indicates something extremely small, and as such is an intensification of minute , minuscule also can refer both to sizes and amounts: a minuscule chess set with peg pieces, designed for travellers; a minuscule slackening of prices after active trading. When the word indicates amount, however, it is more likely than minute to suggest something unimportant or even petty: a minute inspection that turned up only the most minuscule defects in his argument.

Infinitesimal more commonly applies to amounts that are so small as to be incalculable and insignificant for all practical purposes; more strictly, it reflects its relation to the word infinite by referring to something that is infinitely small. The word is often used not so much literally as in exaggeration: making much of an infinitesimal error.

Microscopic and miniature , by contrast, refer most often to size. Microscopic literally refers to something too small to be seen without the aid of a microscope: the abundance of microscopic organisms that flourish in the sea. Miniature , on the other hand, refers to something that is small but by no means invisible or even difficult to see with the naked eye. It suggests most strongly the scaling down of something to small size, as a model. The word relates, by derivation, to small-sized paintings and can still apply in this way. For other things, the word may carry a note of amazement or wonder at the effective job of reducing the proportions of something; it can also suggest an effect of quaintness: a miniature doll’s-house; a miniature castle where children could fight imaginary battles.