* Simple: The gardener applied a protectant to the young seedlings to shield them from pests.
* Descriptive: A layer of protectant on the wooden furniture helped to prevent scratches and water damage.
* Technical: The laboratory technician used a special protectant to preserve the delicate specimens.
* Figurative: Her kindness was a protectant against the harsh realities of the world.
* With a noun: The sunscreen served as a protectant against harmful UV rays.
The meaning of "protectant" is something that protects, so you can use it in any context where something is being protected from harm.