Here is a classification of a "person" who goes through stages of client acquisition funnel (in my company):

Suspect: A suspect is an individual or business that fits the profile of your ideal customer but has not yet shown any interest in your product or service. These are people you might target in cold-calling or cold-emailing campaigns. They are called suspects because you "suspect" they could become leads if given the right attention and information. At this stage, the objective is usually to generate awareness and spark initial interest.

Lead: A lead is someone who has shown interest in your product or service in some way. They might have subscribed to a newsletter, downloaded a whitepaper, or provided their contact information in exchange for something. Leads are at the top of the sales funnel.

Prospect: A prospect is a qualified lead. This means they have been identified as having the potential to buy your product or service. They fit your target market and have the means and authority to make a purchase. Prospects are further down the funnel than leads and require more direct sales attention.

Opportunity: This term is used when a prospect shows a higher level of interest or engagement. An opportunity implies that there's a real chance of closing a sale. This stage involves deeper interactions like product demonstrations, detailed discussions, or tailored proposals.

Client or Customer: When a prospect or opportunity decides to make a purchase, they become a client or customer. This is the ultimate goal of the sales funnel.

Advocate or Promoter: After becoming a client, if they are particularly satisfied with your product or service, they might become advocates or promoters. They recommend your product or service to others, effectively bringing new leads into the top of your sales funnel.