Question: For a planet, we can colloquially refer to its period of rotation as a "day" and its period of revolution around its parent star as a "year." Some worlds have unique terms, such as Martian days being referred to as "sols", but the principle is the same: one word for rotation around its axis, another for revolutions around the star.

Is there an equivalent word for the period of a moon's revolution around a planet? On Earth it roughly lines up with a "month," but multi-moon planets would have different periods for each moon. 

If I was in charge of timekeeping for a mission to Europa or Ganymede, what term would I use to refer to the period of time it takes for the moon to complete one orbit of Jupiter?

Answer: 
You should use one of the precisely defined terms of specific measures of orbital period, which are described on [this Wikipedia page](https://en.wikipedia.org/wiki/Orbital_period).

You might get away with just "orbital period" is you're not using it in a context that requires precision.

For length of day there's [synodic day](https://en.wikipedia.org/wiki/Synodic_day) as well as sidereal period. There's a discussion on the difference between these [here](http://cseligman.com/text/sky/rotationvsday.htm).
Adding to [@stephenG's answer](https://astronomy.stackexchange.com/a/21239/7982), the related Wikipedia page [Lunar month](https://en.wikipedia.org/wiki/Lunar_month) can be used to get an idea of what the various terms mean.

I have to agree though that one should probably try to get away with just using the word month while distracting the person you're talking to (cough or drop something) and then quickly moving on, because any term that's more precise will have a very specific definition, and if someone says "Wait, don't you mean a *blah-blah-blah* month?" you'll have to stop figure out if you do or don't!

| kind | frame - or - criteria | Earth's moon (days) |
| --- | --- | --- |
| sidereal | inertial wrt stars | 27.321661 |
| synodic | rotating with Sun-Earth | 29.530588 |
| draconitic (or draconic) (or nodal) | orbital plane (precesses) time between ascending nodes | 27.212220 |
| anomalistic | time between periapses | 27.554551 |
| tropical | time between alignments of Moon's axis with the planet-moon line | 27.321582 |