prospective

(obsolete) The scene before or around, in time or in space; view; prospect.

(obsolete) A perspective glass.

1613 March 2 (first performance), Francis Beaumont, “The Masque of the Inner-Temple and Gray’s Inn, Gray’s Inn and the Inner-Temple;[…]”, in The Dramatic Works of Ben Jonson, and Beaumont and Fletcher:[…], volume IV, London: […] John Stockdale,[…], published 1811, OCLC 910211381, page 573, column 2:

[T]hey [two pavillions] were trimmed on the inside with rich armour and military furniture, hanged up as upon the walls; and behind the tents there were represented, in prospective, the tops of divers other tents, as if it had been a camp.

(informal, often plural) A prospective (potential) member, student, employee, date, partner, etc.