A prospect is a potential customer – an individual or an organization – that matches your ideal customer profile and might be interested in buying from you.
In terms of a typical sales funnel, prospects typically sit between a lead and an opportunity.
In other words, a prospect is a sales qualified lead that hasn't shown a clear intent to buy yet.
The definition of a sales prospect might differ from organization to organization. For example, they may or may not show interest in your product, be involved in two-way communication with a salesperson, etc.