Correct spelling, explanation: vertical comes from the Latin word vertex and it used to mean directly overhead, which is similar to the modern meaning. Grammatically, vertical functions mainly as an adjective, but it can also be a noun. It is worth noticing that it is spelled with -al at the end.

Definition of vertical:
1. adjective/noun – refers to something which is directed upright:
Put the candle in a vertical position, otherwise, it will mess up the table.
The steel construction will be raised to the vertical with the use of a crane.

Expressions with vertical:
Some common expressions include vertical line, vertical expansion, and vertical position.

Incorrect spelling, explanation: a common mistake made by many learners and native speakers of English is to spell the word vertical as verticle, which is wrong. The mistake probably comes from the fact that both endings are common for adjectives and, as they are similar, it is easy to confuse them.