Covariance:

A measure of influence of one dependent variable to another, covariance presents the weighted correlation among two dependent variables.

Covenant:

A set of limitations imposed by a lender on a borrower regarding how the borrower must function the business for which the capital is being borrowed  Violation of debt covenants is grounds for recalling a loan.

Cover Letter:

Letter to accompany a resume, giving a recruiter with an introduction to a candidate.  Should only be one page long and should briefly indicate how a candidate learned of the position, two to three reasons why the candidate should be considered for the job, and follow-up steps the candidate will pursue.