Nuts and Bolts: iso- prefix.

Isos is the Greek for equal: but, as it turns out, some are more equal than others.

There's the isobar sort of equal, where a line on a map joins points of equal atmospheric pressure; and then there's the isomer sort of equal, where various chemicals are made of the same atoms, but these atoms are joined together in different arrangements.

The isobar sort of equal, used on maps and charts, gives us isobath (equal depth of water) isochime (equal water temperature) isochor (equal volume of a fluid when temperature and pressure change) isochrone (equal time of travelling to one particular point) isogloss (a line surrounding the area of some linguistic feature, such as a pronunciation) isohel (equal sunshine) isonome (equal abundance of a plant species) isopach (area of equal thickness of a rock stratum)  isotach \(equal wind speed) isothere (equal summer temperature) and isotherm (equal temperature).

There's also the very useful isopleth, which joins areas on a chart or map of equal whatever-it-is-you-need-to-join up.

The isomer sort of equal gives us (for example) isochromatic, which describes things that are the same colour, and isomerous, which describes things (usually pants) which have equal numbers of parts or markings.

Nearly all English iso- words are one or the other, except those that are to do with isolation which, pleasingly, stand pretty-much alone.

Word To Use Today: one beginning iso-. Isolation comes from the Latin insulātus made into an island.