The term FILLER HOURGLASS is composed of two words, the first being 'FILLER' which is a four letter word meaning 'a thing used to fill a gap or space' and the second being 'HOURGLASS' which is an object used to measure time. The crossword solution for the term FILLER HOURGLASS is SAND, which is a granular material composed of finely divided rock and mineral particles. SAND is often used as a FILLER material in hourglasses, as it is able to flow freely through the narrow neck of the hourglass and can be easily measured by the amount of time it takes for the SAND to pass through the hourglass.