What's the difference between senary and septenary?

Senary

Definition:

• (a.) Of six; belonging to six; containing six.

Example Sentences:

• (1) (In view of recent evidence of the specific requirement of two cations, the complex is accurately described as senary).

Septenary

Definition:

• (a.) Consisting of, or relating to, seven; as, a septenary number.
• (a.) Lasting seven years; continuing seven years.
• (n.) The number seven.

Example Sentences: