I. ə̇ˈfektiv, eˈ-, ēˈ-, -tēv also -təv adjective
Etymology: Middle English, from Middle French or Late Latin; Middle French effectif, from Late Latin effectivus, from Latin effectus (past participle of efficere to bring about, accomplish, effect) + -ivus -ive — more at effect
1.
a. : capable of bringing about an effect : productive of results
an air-cooled motor was more effective than a witch's broomstick for rapid long-distance transportation — Lewis Mumford
a new organization which would be strong where the league had been weak, … effective where the league had been fumbling — G.L.Kirk
his arm was too badly injured to deliver an effective blow — L.C.Douglas
b. : capable of having its normal effect : able to function normally
at 26,000 feet none are able to retain effective consciousness … without oxygen — C.H.Best & N.B.Taylor
2. : marked by the quality of being influential or exerting positive influence:
a. : exerting authority : carrying weight
the countries represented had virtually all the effective power in the world — M.W.Straight
his effective career began inauspiciously
b. : able to accomplish a purpose : efficient
persons who will do nothing unless they get something out of it for themselves are often highly effective persons of action — G.B.Shaw
c. : impressive , cogent , telling
an effective if not eloquent preacher — E.W.Knight
equally effective in portraiture, landscape, and still life — Current Biography
d. : pleasing , satisfying
a most effective substitute for the conventional Christmas tree — American Guide Series: Louisiana
3.
a. : capable of being used to a purpose
his handwriting was still so bad he couldn't take effective notes — Sloan Wilson
the effective value of our annual income for scholarship endowment has been diminished — J.B.Conant
b. : equipped and ready for service — used especially of military forces
the fort was held by about 100 effective soldiers
4. : actual
committed the blunder of confusing the increased load of equipment and the increased expenditure with the quantity of effective work done — Lewis Mumford
the number of effective wage earners, excluding workers absent for the whole of one week, fluctuated — Collier's Year Bk
a gain in housing units in response to effective demand
5. of a verb form or aspect : expressing the final point of an action or state or a result attained
6. : taking effect : valid , operative
the following resignations were accepted effective during the academic year under review — J.B.Conant
the order was effective as of June 7
7. of the publication of a taxon : accompanied by sale, exchange, or other distribution of printed matter containing a new taxon or new combination — see valid 5b
8. of a natural population : interbreeding
Synonyms:
effectual , efficient , efficacious : effective may indicate the power to produce an effect or the actual production of an effect
we are calling on men and women and property and money to join in making our defense effective — F.D.Roosevelt
Bob had rebuked him after all, and his rebuke, though less hurtful than Sir James's, had been even more effective — Archibald Marshall
effectual may apply to what has accomplished an intended result and may approach the connotations of decisive
the powers of sovereignty and the eminent domain were ceded with the land. This was essential, in order to make it effectual, and to accomplish its objects — R.B.Taney
an appeal to the emotions is little likely to be effectual before luncheon — W.S.Maugham
efficient may designate that which is actually operative; it may apply to smooth operation with a maximum of work or output accomplished with a minimum of effort
it should be obvious that it is the conditions producing the end effects which must be regarded as the efficient causes of them — M.F.A.Montagu
a strong tendency to break up cumbersome estates into small, efficient farms — Allan Nevins and H.S.Commager
since the steam engine requires constant care on the part of the stoker and engineer, steam power was more efficient in large units than in small ones: instead of a score of small units, working when required, one large engine was kept in constant motion — Lewis Mumford
efficacious may suggest possession of potent, powerful, or proper qualities productive of effective power
in their opinion, the flesh and blood of an enemy killed in battle is the most efficacious of all charms and makes a first-rate drug — J.G.Frazer
the pained expression that he had long since found to be much more efficacious than anger — Edith Wharton
II. noun
( -s )
: one that is effective: as
a. : a soldier equipped, fit, and ready for active service
the troop figure includes quartermasters, MPs, and signal, transportation, and medical corpsmen to a total of perhaps half its effectives — T.H.White b. 1915
b. : an effective aspect of a verb or an effective verb form