Incorrect spelling, explanation: secundary is a mistake because the word secondary is formed from the ordinal number second. This mistake may come from taking the word more directly from Latin secundus (in many languages this spelling is used more or less directly), but the English form was created from French secondaire, and existed as secondarie before it was simplified to today’s secondary.

Correct spelling, explanation: the adjective secondary is spelled like this because of the root second (an ordinal number). In the past, the word was more French-spelled secondarie (Old French secondaire) and then it evolved to secondary. Secundary is at the same time an incorrect form.

Definition of secondary:
adjective, less important, coming after something else; also: a type of school after primary school
After completing his degree in physics, Tom decided to pursue a secondary degree in computer science to increase his job prospects.
Lucy is growing up so fast; she’s already in secondary school!
The city’s main airport was closed due to bad weather, so all flights were diverted to the secondary airport on the outskirts of town.

Collocations with secondary:
secondary education, education that follows primary education
During his time in secondary education, John discovered a passion for chemistry and now he is pursuing this career.
secondary colours, colours outside of the primary colours, created by mixing primary colours
The secondary color orange is often used in advertising to create a sense of excitement and urgency.

Incorrect spelling

Incorrect spelling

Incorrect spelling