There are two types of lexis:
Low Frequency Lexis (LFL),
and High Frequency Lexis (HFL)
LFL are words that aren't commonly used. For example, LFL for a British person:
Hot, Sunny, and Happy.
LFL for a normal person:
Established, ought, lexis, demographic & abundence.
HFL are words that are often used, such as;
Is, the, and, but and because.