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ac·ti·vate

(ăktə-vāt′)

tr.v. ac·ti·vat·ed, ac·ti·vat·ing, ac·ti·vates

1. To set in motion; make active or more active.

2. To organize or create (a military unit, for example): activate the National Guard.

3. To treat (sewage) with aeration and bacteria to aid decomposition.

4. Chemistry To accelerate a reaction in, as by heat.

5. Physics To make (a substance) radioactive.

6. Biology To convert (a molecule or cell) into a form that carries out a specific action: activate an enzyme; activate B cells.

ac′ti·vation n.

acti·va′tor n.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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