What is a working definition of a "client" in the executive search
business? Include the amount of time a client remains a client vs a
prospect.

In executive search, when an employer places a job order for a
specific position, signs a contract agreeing to the fees, that
employer has become a client and would be bound to pay fees if an
employee presented by the search firm was hired as a result of that
introduction. Contracts gnerally hold up for a year. For example, a
search firm finds and introduces a prospective employee. The hire does
not occur at that time, but 9 months later, the employer once again
becomes interested in that prospective employee and hires him or her,
the search firm is due the agreed apon fee. Any employer is a
potential prospect for a search firm, but without a contract regarding
the introduction of a specific employee regarding a specific job
order, there are no obligations.