Depends on the context. However, generally it is a "condition" that must be meant for the purchase contract to be binding. Could be in a number of areas but not limited to, such as the following, seller's bank must approve as in a short sale, previous home must sell, home appraisal required, or some similar condition.
Contingent usually refers to a condition that needs to met prior to the contract being ratified.
Purchase agreements have many contingencies written in to the contract - financing, appraisal, loan and inspection. As per the contract buyers have 17 days to remove these contingencies.
If you discover that a house you found on the internet is contingent you may still be able to submit a back-up offer. In that way you will be first in line in case the first buyer doesn't qualify, or decides not to buy the house.
It would be nice to let us know how the word is being used. Give us the sentence it which this word used.
Vivien L Biggs, PLC
Prudential Arizona Properties
Check MLS for homes on my website