Split seconds are a unit of time that measure the smallest fraction of a second. They are often used to measure the speed of events that happen in a very short amount of time. The term 'split seconds' can also be used to refer to two or more events that occur at the same time. In this crossword, the solutions for SPLIT SECONDS are JIFFS (5 letters) and INSTANTS (8 letters). JIFFS is an acronym for 'joint interval fractional frequency standard' and is a unit of time equal to one thousandth of a second. INSTANTS is another word for split seconds and refers to a very brief moment in time.