Correct spelling, explanation: the origin of the word medieval is the Latin word medium aevum and it referred to the historical period in Europe. The original English spelling used to be more similar to the Latin one as it had the form mediaeval. Later, however, it was shortened to medieval and today it is considered to be the only correct form.

Definition of medieval:
adjective – related to the period of the Middle Ages in European history,
Last holiday we went on a fascinating tour around the medieval towns of England.

Expressions with medieval:
Some common expressions include medieval town, medieval art, and medieval building.
This lovely medieval town is extremely popular among history lovers.
The church is filled with some wonderful examples of medieval art.
The authorities of the town decided to restore this beautiful, medieval building.

Incorrect spelling, explanation: in the past, the word medieval used to have an extra -a letter in the middle of the word, which gave the form mediaeval. For many years it was the correct form and it can still be found in some texts from older periods. Later, however, the -a letter disappeared and now the only correct form is medieval.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling