Certian vs Probable - What's the difference?

As an adjective probable is

likely or most likely to be true.

Certian has no English definition. It may be misspelled.

(en adjective)

Likely or most likely to be true.

It's probable that it will rain tomorrow.

The probable source of the failure was the mass of feathers in the intake manifold.

Likely to happen.

With all the support we have, success is looking probable .

Supporting, or giving ground for, belief, but not demonstrating.

probable''' evidence; '''probable presumption

(Blackstone)

(obsolete) Capable of being proved.

* improbable

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