The term 'slide uncontrollably' can be broken down into two crossword solutions: SKID (4 letters) and SLEW (4 letters). SKID is a verb meaning to slide or slip on a surface, usually due to loss of traction. It is often used in the context of vehicles, such as cars skidding on wet roads. SLEW is also a verb, meaning to move or turn suddenly and rapidly. It is often used to describe a large, uncontrolled movement, such as a person or vehicle slewing out of control. Together, these two words describe an uncontrolled sliding motion.