For certain and With certainty

For certain adverb - Definitely or positively (`sure' is sometimes used informally for `surely').

With certainty and for certain are semantically related in without doubt topic. In some cases you can use "With certainty" instead an adverb phrase "For certain".

For certain and with certainty are semantically related in without doubt topic. Sometimes you can use "For certain" instead an adverb phrase "With certainty".