Nuts and Bolts: plane/plano- words.

 Plano- means flat, that is, existing in one plane but probably not a 747...

...which invites the question: what's so flat about an aeroplane?

Well, the wings are flat (ish), obviously. So that's why it must be an aeroplane. 

Yes?

Nope.

Prefix or suffix To Use Today: plane/plano. Most words that begin with plano- are from the Latin word plānus, which means flat or level. These include the names of lenses such as plano-concave, which means flat on one side and cave-shaped on the other:

illustration by ElfQrin

Then there's words like planometer, which is a device for making sure metal surfaces are completely flat, and planography, which is any printing method which calls for a flat surface.

Plane sailing is when you plot a course without bothering about the fact that the Earth is spherical (which is not necessarily plain sailing).

And then there are other plano- or plane words which confuse everybody. A planogamete is a type of animal cell which isn't particularly flat but moves about by itself, and the plano- here comes from the Greek planaein, to wander (the word planet comes from the same word, because the planets appear gradually to wander across the constellations in the sky).

An aeroplane is a machine which wanders through the air.

You know what? Sometimes thinking about things just makes them trickier.