stifle
STY-fulverbMeaning to hold back, as a yawn or a laugh; also, to smother
Memory hook a STIFF hand: STIF-le the yawn. In the middle of the long concert, Professor Edwin clamps a stiff hand over his mouth to hold in a giant yawn: he stifles it.
Grandpa stifled a yawn during the long speech.
In context Too many strict rules can stifle creativity; when every drawing has to look the same, students stop trying new ideas.
Similar smother, muffle, hold back, repress
Opposite release, express, encourage