un amusing (adjective) serious: crucial, weighty
Sinonime: arduous,
dangerous,
deep,
difficult, far-reaching, fateful,
fell,
formidable,
grave,
grievous,
grim,
hard,
heavy,
important,
laborious,
major, meaning business,
meaningful,
menacing,
momentous, no joke, no laughing matter, of consequence, operose, out for blood, playing hard ball,
pressing,
severe,
significant, smoking, sobering,
strenuous, strictly business,
threatening,
tough,
ugly, unamusing, unhumorous,
urgent, worrying
Antonime: light,
minor,
trivial,
unimportant, unserious