Definition of centry:
(n) :
Alternative form of century. [A period of one hundred consecutive years; often specifically a numbered period with conventional start and end dates, e.g., the twentieth century, which stretches from (strictly) 1901 through 2000, or (informally) 1900 through 1999. The first century AD was from 1 to 100.]
(n) :
Obsolete form of sentry. [A guard, particularly on duty at the entrance to a military base.]