Were the Invincible-class ships escort carriers?

Should the Invincible class be considered modern escort carriers?

No; their larger air groups and ability to perform both strike and escort tasks make light carrier the better description.

An escort carrier generally fielded a small air group for a narrow supporting role. The Invincible class could combine Sea Harriers and Sea Kings in an air group of roughly forty aircraft, giving it capabilities closer to a light fleet carrier. It could perform air defense and broader carrier tasks at the same time instead of serving one convoy-support function. Mission breadth and air-group scale both place the class above the escort-carrier category.