What is another word for most straight-faced?
Pronunciation: [mˈə͡ʊst stɹˈe͡ɪtfˈe͡ɪsd] (IPA) 
When it comes to expressing composure or seriousness, the phrase "most straight-faced" comes to mind. However, there are several synonyms that can be used to convey the same or a similar meaning. Words like stoic, impassive, unemotional, expressionless, poker-faced, and stolid all denote a person's ability to maintain a serious demeanor and avoid betraying any emotions or feelings. Resolute, determined, and unwavering are a few other terms that highlight the seriousness and depth of a person's conviction or dedication, without necessarily implying a lack of emotion. Ultimately, one's choice of synonym for "most straight-faced" will depend on the specific context and message they want to convey.
