a flight in which the aircraft pilot is unaccompanied | any specific behavior |
any activity that is performed alone without assistance | the trait of being active; moving or acting rapidly and energetically |
a musical composition for one voice or instrument (with or without accompaniment) | an organic process that takes place in the body |
| a process existing in or produced by nature (rather than by the intent of human beings) |
| the state of being active |
| (chemistry) the capacity of a substance to take part in a chemical reaction |