Ism what is this suffix mean?

Greek: "Ism" is a suffix, (word ending) derived from Greek. It's use in the medical field means a condition or state. Here is an example; Hypothyroidism-the condition or disease of low thyroid. Hypo means low, thyroid is the gland and "ism" denotes the condition, the term does not describe the cause of the disease. I hope this answers your question.