1 [+expresión, tono] serious
¿por qué estás hoy tan serio? why are you (looking) so serious today?; su padre es muy serio his father's a very serious person; se quedó mirándome muy serio he looked at me very seriously; he stared gravely at me; pareces muy serio you're looking very serious; ponerse serio: se puso seria al ver la foto she went o became serious when she saw the photo; me voy a poner seria contigo si no estudias I'm going to get cross with you if you don't do some studying
en serio seriously; tomar un asunto en serio to take a matter seriously; no hablaba en serio I wasn't serious
¿lo dices en serio? are you serious?; do you really mean it?
4 (fiable) [+persona] reliable; [+trato] straight; honest
es una persona poco seria he's not very reliable; una empresa seria a reliable firm; no es serio que ahora decidan echarse atrás it's not very responsible of them to back out now
el negro es un color demasiado serio para una niña black is too serious o severe a colour for a young girl; lleva un traje muy serio he's wearing a very formal suit