No. Gooder is not a word, do-gooder is.
Do-gooder is defined as someone whose desire and effort to help people (such as poor people) is regarded as wrong, annoying, useless, etc.
Synonyms for do-gooder:
altruist
humanitarian
philanthropist
volunteer
Do-gooder sample sentences:
There's no beating "The Interrupters" as a prime example of the so-called "do-gooder" documentary, except that it's actually good.
She was what they called a "do-gooder " and she had with her a list of posts in the homes of well-off Italian families.
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