This is an irregular feature - both in frequency and oddness - dedicated to a word I came across that I have never previously used.
gossypiboma, n. A surgical sponge accidentally left in the body of a patient after surgery. It is derived from the Latin word "gossypium" (cotton) and the Swahili word "boma" (place of concealment).
If the object does not cause infection or obstruction, it is usually left in the patient. However, pateients sometimes develop acute sepitcemia when a foreign object like this is inadvertantly left behind after surgery.