- in a serious manner: He shook his head seriously.
- to an alarmingly grave extent: seriously ill.
- with genuine, earnest intent; sincerely: Seriously, kids, we have to get home before dark.
- in a serious manner or to a serious degree
- informal extremely or remarkablyseriously tall
adv.c.1500, from serious + -ly (2). To take (something) seriously is from 1782.