idiopathic

of unknown cause

induration

hardening

inert

not active; substance that doesn’t affect you

infarct

death of tissue because of lack of blood supply

interferon

agent that acts against viruses

intraperitoneal

into the abdominal cavity

intrathecal

into the spinal fluid

intravesical

in the bladder

intubate

the placement of a tube into the airway

ischemia

decreased oxygen in a tissue (usually because of decreased blood flow)