This is a condition in which the lens of the eye loses its ability to focus, making it difficult to see objects close-up. The condition is associated with aging and is progressive (gets worse).
See What are myopia, hyperopia, astigmatism, and presbyopia? [1]
See other terms from Glossary of Eye Terminology. [2]
Links:
[1] http://www.visionaware.org/what_are_myopia_hyperopia_astigmatism_presbyopia
[2] http://www.visionaware.org/glossary