to suffocate (a person or animal) or prevent (a person or animal) them from breathing freely
We were nearly stifled, it was so hot in there
to suppress (a yawn, a giggle, etc)
to curb or repress (something), or prevent its development
They seemed bent on stifling individual talent and initiative
They tried to stifle the rebellion
to be unable to breathe freely; to suffocate
stifling adj
stiflingly adv
[alteration of Middle English stuflen, perhaps from Old French estouffer to smother]