From the Latin "primus" (first):
* Primary: Most important, first in order.
* Prime: First in importance, excellent.
* Primitive: Relating to an early stage of development.
* Primate: A mammal of the order Primates, including monkeys, apes, and humans.
* Primogeniture: The state of being the firstborn child, especially the right of the firstborn son to inherit his father's estate.
From the Latin "primus" (first), with a slightly different meaning:
* Primeval: Belonging to the earliest period of time, prehistoric.
* Primal: Basic, fundamental, instinctive.
Other words:
* Primp: To make oneself look attractive, especially by spending a lot of time on one's appearance.
* Prim: Formal, proper, and slightly old-fashioned in manner or appearance.
Note: There are also some words that are related to "prim" but do not directly use the root word, such as "priggish," "primacy," and "prior."