Use 'stolid' to describe someone who stays calm and doesn't show feelings in stressful situations. Despite the chaos, the security guard's stolid demeanor reassured everyone.
Pro Tip 2/3
No Emotional Reaction
'Stolid' implies not reacting with visible emotions where one might be expected to. Her stolid face betrayed no joy at the surprise party.
Pro Tip 3/3
Misinterpretation Risk
Be aware that a 'stolid' person may be wrongly perceived as insensitive or uncaring. His stolid reaction to the news made some think he was indifferent.