1. To make active or more active
2. To enable or turn on
3. To make (substances) radioactive.
4. To make more adsorptive; of metals.
5. To aerate (sewage) so as to favor the growth of organisms that decompose organic matter; SYN. aerate.

(Alternate spelling: energise).
To use strength in action; to act or operate with force or vigor; to act in producing an effect.

1. To begin or set in motion; SYN. go, get going.
2. To begin work or acting in a certain capacity, office or job; SYN. take up.
3. To get going or set in motion; SYN. start up.
4. To get off the ground; SYN. start up, begin, embark on, commence.
5. To play in the starting line-up, in team sports.

1. To become hostile towards; SYN. turn upon.
2. To produce suddenly or automatically, as of tears of charm.
3. When people or animals that you had good relations with turn on you, they stop being friendly and try to hurt you.