Adjective

(en adjective)

Joyful, glad, taking pleasure in being alive. Not depressed or sad.

The lighthearted young lovers ran over the hills.

Enjoyable lack of seriousness, not grave.

His lighthearted banjo was appreciated because it relieved the tension in tight situations.

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.