SMOOTH GLABELLA

Fun anatomy fact: the glabella is the patch of skin between your eyebrows, unless you have a unibrow, in which case no glabella for you. The word was adopted in the times of Shakespeare from the Latin word glabellus, which meant both "without hair" and "smooth", a logical extension. This further derives from the root glaber, with the same meaning, from the Proto-Indo-European reconstruction gladh, meaning "smooth" but also sometimes "shiny". Glaber also gave us the equally obscure word glabrous, which means "smooth" as well, and gabbro, an igneous rock that's, you guessed it, pretty smooth. There are several relatives stemming from gladh, including glad, the word for "happy" itself, glare, glass, gold, and even yellow, all by influence of the "shiny" definition. Usage of glabella really spiked in the '40s and has been diminishing since.