Effective

[ih-fek-tiv] /ɪˈfɛk tɪv/

adjective
1.
adequate to accomplish a purpose; producing the intended or expected result:
effective teaching methods; effective steps toward peace.
2.
actually in operation or in force; functioning:
The law becomes effective at midnight.
3.
producing a deep or vivid impression; striking:
an effective photograph.
4.
prepared and available for service, especially military service.
noun
5.
a member of the armed forces fit for duty or active service.
6.
the effective total of a military force.
/ɪˈfɛktɪv/
adjective
1.
productive of or capable of producing a result
2.
in effect; operative: effective from midnight
3.
producing a striking impression; impressive: an effective entrance
4.
(prenominal) actual rather than theoretical; real: the effective income after deductions
5.
(of a military force, etc) equipped and prepared for action
6.
(physics) (of an alternating quantity) having a value that is the square root of the mean of the squares of the magnitude measured at each instant over a defined period of time, usually one cycle See also root mean square
noun
7.
a serviceman who is equipped and prepared for action
adj.

late 14c., from French effectif, from Latin effectivus “productive, effective,” from effect-, stem of efficere (see effect (n.)). Effectively in the sense of “actually” is attested by 1650s. Related: Effectivity.