1. 被迫的;强迫的;非自愿的
A forced action is something that you do because someone else makes you do it.

2. 不得已的;不得不做的
A forced action is something that you do because circumstances make it necessary.

3. 不自然的;勉强的
If you describe something as forced, you mean it does not happen naturally and easily.

1. lacking spontaneity
not natural

e.g. a constrained smile
forced heartiness
a strained smile

Synonym: constrainedstrained

2. made necessary by an unexpected situation or emergency

e.g. a forced landing

3. forced or compelled

e.g. promised to abolish forced labor

4. produced by or subjected to forcing

e.g. forced-air heating
furnaces of the forced-convection type
forced convection in plasma generators