Successful in producing a desired or intended result
an effective treatment
Not successful in producing a desired or intended result
Effective or productive in relation to its cost
An efficient cause.
The date on which an order, ruling, appointment, etc., takes effect.
The mass of something as calculated or inferred from its effect in a particular context; (Physics) the mass that needs to be assigned to a particle if the usual equations of motion are to hold in a situation where they do not strictly apply; specifically the mass that an electron appears to have in a crystal lattice, where its motion is affected by electric and magnetic fields.
Money in the form of coin, as opposed to paper money.
The range within which a missile, weapon, or firearm is effective.
The diameter of the widest beam of light incident on an optical system that goes to form an image; also in extended use (e.g. in connection with radio waves or particle beams).
The level of demand that represents a real intention to purchase by people with the means to pay
The temperature of an object calculated from the radiation it emits, assuming black-body behavior