What is the medical term meaning pretending to be sick?

You are thinking of "Malingering" . This is intentionally faking illness in order to gain some perceived benefit, like getting out of some kind of work or duty. A malingerer will go so far as to exaggerate or even produce symptoms in order to appear ill. You might have had "Hypochondriasis" in mind, but Hypochondriasis is the fear of being ill, even though there are no symptoms. This may be more than you wanted to know, but there is another related disorder called "Factitious Disorder" where a person will fake the sick role, as in malingering, but there is no external incentive. The reasons for this disorder are more psychological in nature, rather than to gain some real benefit. There is more in the Diagnostic and Statistical Manual of Mental Disorders, if you want to do a little digging.