[Alneyan]

*Pops in discreetly, while nobody is watching*

Frolic (pronounced... erh, quite like frolic actually):
Noun:
1) Merriment: Fun and frolics
2) A gay, carefree time.
Verb:
1) To behave playfully without any inhibition
2) To engage in merrymaking

The adjective form is "frolic" or "frolicsome", both of them being somewhat dated. It shouldn't be difficult to guess the meaning of these two adjectives though.

And while I am at it:

Mien
Noun:

1) Bearing or manner, especially one revealing an inner state of mind
2) Appearance or aspect, especially the typical expression on their faces.

If you are interested in idle speculation, the French word "mine" has more or less the same meaning (along with the other meanings of the English "mine"), although the French word is quite informal whereas "mien" seems formal or even literary.