indubitably Edit
Adverb
    in a manner or to a degree that could not be doubted
eg: it was immediately and indubitably apparent that I had interrupted a scene of lovers

Entries from Olam Open Database

Indubitably(adjective)::
    നിശ്ചയമായി,
    നിസ്സംശയമായി,
Indubitably(noun)::
    നിസ്സംശയം,

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