The term 'PREFIX WITH SECOND' refers to two prefixes, milli- and nano-, which are used to denote fractions of a second. Milli- is derived from the Latin mille, meaning thousand, and is used to denote one thousandth of a second. Nano- is derived from the Greek nanos, meaning dwarf, and is used to denote one billionth of a second. Both milli- and nano- are commonly used in scientific contexts to measure very small intervals of time.