Often as we read old documents, we find words that are unfamiliar to us. Old occupations and old diseases are likely the two most common. But that doesn't need to stump us or stop us in understanding more about our ancestor.
A common cause of death for women in the 1800s was Milk Fever - an infection following childbirth but one that people thought was associated with nursing women. Milk Leg was another complication of childbirth - today we know this to be caused by clotting in the legs following childbirth, but in the 1800s this again was associated with nursing mothers.
There were a myriad of illnesses commonly listed on death records but that are unfamiliar to us in the 21st century. Here's a list to some of the more common causes of death in the 1800s: http://rmhh.co.uk/illness.html