Betty wrote, “I know that the word part –post- means after. How does that tie into the word postulate, a self-evident assumption or axiom that is used in geometry?”
There is no connection. With surprising frequency, word parts with no connection to each other accidentally wind up with identical spelling, the very same letter sequence, even though the meaning and the source are miles apart.
A classic example is the word part –ped-. It can mean foot (pedal), child (pediatrician), or soil (pedocal). Another example is the word part –in-. It can mean inside (instill), but it can also mean not (insane).
Back to –post-. Postulate comes from a Latin word that means a demand, a forceful request. Other words sharing that same root are expostulate, postulant, and postulative. The -post- that means later in time shows up in words such as post-game, postpartum, and postmortem. A slightly different shade of meaning, behind in position, shows up in postaxial, posterior, and postchoroid.
Post—the sturdy piece of timber—comes from another source entirely, and has no connection to the word parts above.
Available from McFarland & Co.: Word Parts Dictionary, 2nd edition
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