This is the 201st most frequent Spanish word.
mayo
"May" (the fifth month of the year).
Here, 'mayo' is used as a noun to represent the month of May.
El cinco de mayo es una celebración importante en México.
The fifth of May is an important celebration in Mexico.
In this sentence, 'mayo' is short for 'mayonesa,' which means mayonnaise, and is used as a culinary term.
Prefiero usar mayonesa en mi sándwich en lugar de mostaza.
I prefer to use mayonnaise on my sandwich instead of mustard.
Here, 'mayo' is used as an adjective (greater, older) in a more formal and poetic sense.