activate

Built from active plus the verb-making -ate, the word means "make active" in every use; what changes is what counts as active. Here the sense is general and often figurative. One activates an economy or a team's drive, something with energy of its own that needs only a push. Where a switch or trigger is involved, the mechanical sense takes over.

Software sellers made this a commercial step rather than a technical one. The program already runs, but entering a license key lifts the feature locks, usage caps or time limits of the trial version. Unlock is the everyday synonym. Unlike switching a device on, activating software changes what a working program is permitted to do.

In biology the switch is usually a precise chemical change: a phosphate group is added, a chain is cleaved or a cofactor binds, and an enzyme or signaling protein begins its work. The meaning is functional rather than merely reactive. An activated protein does its job, and that is what separates this use from the chemist's "more reactive" sense.

Chemists and physicists use it for a change of state in the substance itself. The molecules are raised to a condition where reaction comes more easily, often by supplying the activation energy needed to reach the transition state. In physics, excite is the near synonym. Keep it apart from the "hasten a reaction" sense, where the object is the reaction rather than the substance.

Here the object is a process, not a material. You activate a reaction, usually with heat, so that more molecules carry enough energy to clear the activation barrier. It is a laboratory word that sits close to accelerate and drive. When the thing being treated is the substance itself, the "more reactive" sense is the one meant.

Nuclear rather than chemical: neutrons or other particles strike a stable material and turn some of its nuclei into unstable isotopes, which then decay. Reactor steel and cobalt samples are typical objects. The substance's chemistry need not change at all; what changes is its nuclei, and so does how safely it can be handled.

Military usage treats a unit as something brought into being by formal order. A squadron, a command or a base is activated, very often in the passive, and given personnel, equipment and a designation. Restoring a unit that was once disbanded is a separate step, called reactivating.

A roster word from team sports: a player is activated from the injured or reserve list and becomes eligible to compete again. The usual construction is activate someone from a list. League rules on roster size and the timing of transactions often govern when a team may do it. The act is administrative and is distinct from the player's recovery itself.