i Register
In some senses, irresponsible is marked as archaic. Watch for register when choosing this word.
VERBS
be, seem, sound | become | consider sb/sth
ADV
extremely, grossly, highly, terribly, very
Leaving your young children alone at home would be extremely irresponsible.
completely, totally, utterly, wholly
She completely ignored her duties and spent all day shopping instead.
rather, slightly, somewhat
socially
Dumping waste into the river is socially irresponsible and harms the community.