Millis is a time measurement unit equivalent to one thousandth of a second. It is a commonly used term in science, technology, and engineering. However, there are various synonyms for this term that can be used depending on the context. Some of the synonyms for millis include msecs, milliseconds, thou, thou-seconds, and thousandths of a second. These terms are often used interchangeably to express fractions of a second. It is important to understand these synonyms, as they can help in improving communication and understanding of time-based concepts across different fields. So, next time when you encounter the term millis, keep in mind that its synonyms can be used to convey the same meaning.