1.
principle; general rule
A fundamental rule or standard that guides actions or decisions.
2.
as a rule; in principle
Used adverbially to indicate what is generally the case, implying that exceptions may exist.
When used adverbially (sense 2), it often appears as 原則として or on its own before a statement. This usage implies 'this is the general rule, but exceptions may apply.' Very common in rules, regulations, and official notices.