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J'ignorais qu'il était malade.
I didn't know he was ill.
To not know something.
J'ignorais qu'il était malade.
I didn't know he was ill.
Ignorer = not know (neutral); not ignoring deliberately.
To deliberately ignore.
Il m'a complètement ignorée.
He completely ignored me.
Same verb, both senses; context decides.
From Latin ignorare (not to know).
False friend: ignorer usually means not know, not snub.