What is the noun of exist and measure?

The noun forms for the verb to 'exist' are existence and the gerund, existing.

The Word 'measure' is a noun form, a Word for a unit used to express the size, amount, or degree of something; a plan or course of action taken to achieve something; the rhythm of a piece of poetry or music; a Word for a thing.

The noun forms of the verb to 'measure' are measurer, measurement, and the gerund, measuring.