The direct antonym applicable for the term normal is abnormal.
From a chemical perspective, the antonym is oxidation In normal conversation, an antonym could be "enlargement"
normal.
Normal
Yes
Conventional.
Normal; not law
Normal? I really have no idea
conventional, normal
"Normal" or "Habitual"is the antonym of unconventional.
How about "common"? or "normal"?
The antonym of usual is unusual.
Natural, normal, common, known