Adjective

(en adjective)

Making good, thorough, or careful use of resources; not consuming extra. Especially, making good use of time or energy.

* {{quote-magazine, title=A better waterworks, date=2013-06-01, volume=407, issue=8838

, page=5 (Technology Quarterly), magazine=(The Economist) citation , passage=An artificial kidney these days still means a refrigerator-sized dialysis machine. Such devices mimic

Using a particular proportion of available energy.

Causing effects; producing results.

* Wilson

The efficient cause is the working cause.

Adjective

(en adjective)

Answerable for an act performed or for its consequences; accountable; amenable, especially legally or politically.

* {{quote-magazine, date=2012-03

, author=William E. Carter, Merri Sue Carter , title=The British Longitude Act Reconsidered , volume=100, issue=2, page=87 , magazine= citation , passage=But was it responsible governance to pass the Longitude Act without other efforts to protect British seamen? Or might it have been subterfuge—a disingenuous attempt to shift attention away from the realities of their life at sea.}}

Parents are responsible for their child's behaviour.

Capable of responding to any reasonable claim; able to answer reasonably for one's conduct and obligations; capable of rational conduct.

Involving responsibility; involving a degree of personal accountability on the part of the person concerned.

She has a responsible position in the firm.

Being a primary cause or agent of some event or action; capable of being credited for something, or of being held liable for something.

Who is responsible for this mess?

Able to be trusted; reliable; trustworthy.

He looks like a responsible guy.