Of utterances or demeanour: Resolute, defiant. archaic.

Arising from or indicative of the emotional or mental resilience needed to deal with difficult or… Of looks, voice, etc.

Of the countenance or bearing: Indicating a settled purpose, mind, character, etc.

Having the lips firmly closed, esp. as a sign of determined suppression of emotion; also transferred and figurative. Also, determinedly reticent or…