any specific behavior | a flight in which the aircraft pilot is unaccompanied |
the trait of being active; moving or acting rapidly and energetically | any activity that is performed alone without assistance |
an organic process that takes place in the body | a musical composition for one voice or instrument (with or without accompaniment) |
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 | |