wavelength
WAYV-length · noun
English
Origin
Wavelength comes straight from wave and length, joined to name the distance a wave travels before it repeats itself.
Journey
The word has stayed close to its literal, physical meaning, though it's often borrowed today to describe two people who understand each other easily.
Related words
It shares its two halves plainly with the everyday words wave and length — no hidden roots, just a direct pairing.