seriousShe had a serious look on her face.
earnestAt that time he was an earnest young environmental activist.
soberThe mood of the gathering was sober and reflective.
sombreUKSince their colleague died there has been a very sombre atmosphere in the office.
solemnThe two men fell silent, their faces solemn.
grimHe looked over at Ed, his expression grim.
unsmilingI was greeted by her terse unsmiling face.
dourDespite the dour demeanour, he can laugh at himself.
humourlessUKThey are a notoriously humourless bunch.
po-facedUKinformaldisapprovingPeople sometimes think of the world of classical music as being po-faced, but the opposite is true.