I'd go for: 
    $line =~ s/(gregarious)/\\underline{gregarious}/g &&
    $line =~ s/\\underline\{(gregarious)\}/\\footnote{$1}/;

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Abigail

In reply to Re: Combining two Reg Expressions with substitution by Abigail-II
in thread Combining two Reg Expressions with substitution by cranberry13

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