"illegitimately" in the adverb sense
1. illegitimately, illicitly
in a manner disapproved or not allowed by custom
"He acted illegitimately when he increased the rent fourfold"
2. illegitimately, out of wedlock
of biological parents not married to each other
"this child was born illegitimately"
Source: WordNet® (An amazing lexical database of English)
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