to be reckoned with

From reckon with.

to be reckoned with

1. This term needs a definition. Please help out and add a definition, then remove the text {{rfdef}}.

   a force to be reckoned with

• “to be reckoned with” in the Cambridge English Dictionary, Cambridge: Cambridge University Press.
• “to be reckoned with” in the Collins English Dictionary
• “a force to be reckoned with” in Merriam–Webster Online Dictionary.
• “a force to be reckoned with” (US) / “a force to be reckoned with” (UK) in Macmillan English Dictionary.
• “reckon with” in Longman Dictionary of Contemporary English, Longman.