a very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy; occurs in economically extractable amounts in certain natural gases (as those found in Texas and Kansas)
"The party balloons were filled with helium from the local well, making them float safely without catching fire."
The second lightest chemical element (symbol He) with an atomic number of 2 and atomic weight of 4.002602, a colorless, odorless and inert noble gas.
"During the science fair demonstration, the teacher released helium from the tank to show how its low density allowed the balloon to float effortlessly against gravity."
The name helium comes from the Ancient Greek word for "sun," reflecting how its presence was first theorized in the Sun's atmosphere. Although the suffix -ium is typically reserved for metals, it was likely used by astronomer Norman Lockyer without regard for standard chemical conventions.