Error-Detecting Properties of Languages Stavros Konstantinidis In the context of storing/transmitting words of a language $L$ using a noisy medium, the language property of error-detection is fundamental. It ensures that the medium cannot transform a word from $L$ to another word of $L$. This paper defines some basic error-detecting properties of languages and obtains a few basic results on error-detection. For example, it is shown that the number of synchronization errors that a regular language can detect is bounded by the size of its syntactic monoid. Moreover, some error-detecting capabilities of uniform, solid, and shuffle codes are considered. It is shown that those codes provide certain error-detection either for free or when a simpler condition is satisfied.