The crossword solution for the term 'ACROSS WORD' is TRANS, which is a five-letter word. TRANS is an abbreviation for the word 'TRANSVERSE, ' which means 'lying or extending across something else.' It can also refer to a type of wave that moves in a direction perpendicular to the direction of the wave's propagation. In mathematics, transversality is a concept used to describe the behavior of a function at a certain point. In physics, TRANSVERSE waves are waves that move in a direction perpendicular to the direction of the wave's propagation.