Correct spelling, explanation: the word potential entered English in the times of Middle English from the Latin word potent, which meant being able. At first, it also had the form potent in English and it functioned only as a verb. Later, in the 19th century, the word potential appeared and started to function as a noun and adjective, too.

Definition of potential:
1. adjective – possible to happen under the right circumstances,
He might be our potential customer, but he’s waiting for the price to fall.
2. noun – your ability to succeed or develop yourself,
I feel that I can reach my full potential at this work.

Collocations with potential:
Some common collocations include limitless potential, unfulfilled potential, and develop potential.
He’s been a top football for years now and it still seems that has limitless potential.
This boy is such unfulfilled potential – if only he worked harder.
I believe that this company will help me develop my potential.

Incorrect spelling, explanation: a common mistake made by native speakers of English and its learners is to spell the word potential as potentional. The latter form, however, does not exist in English so make sure you do not use it while writing the word.