effective
The new policy was effective in reducing traffic accidents.
The policy successfully achieved its goal of lowering traffic accidents.
producing a successful result or desired effect
The training program was effective in improving employee productivity.
The program successfully increased how much employees accomplished.
Aspirin is effective for relieving headaches.
Aspirin successfully reduces headache pain.
Often used to describe methods, strategies, or solutions that work well in practice.
in operation or functioning as intended
The law becomes effective next month.
The law will start being enforced next month.
The software update is now effective across all devices.
The update is now working properly on every device.
Used for rules, laws, or systems that are currently active or enforceable.
Collocations
Pro Tip
Avoid redundancy
Don't use 'effective' with words like 'very' or 'extremely'—it's already a strong adjective. Say 'highly effective' only for emphasis in formal contexts.
Gold Rule
Effective vs. Efficient
Use 'effective' for outcomes (e.g., 'The vaccine is effective against the virus') and 'efficient' for processes (e.g., 'The factory is efficient in producing cars').
Word Origin
From Latin *effectivus*, from *effectus* (effect, accomplishment), from *efficere* (to accomplish, from *ex-* 'out' + *facere* 'to make').
Usage Notes
Avoid confusing with 'efficient'—'effective' means achieving a goal, while 'efficient' means achieving it with minimal waste. 'Effective' focuses on results, not necessarily speed or cost.