Lanthanum and Lanthanon

Lanthanum noun - A white soft metallic element that tarnishes readily; occurs in rare earth minerals and is usually classified as a rare earth.

Lanthanon and lanthanum are semantically related. In some cases you can replace term "Lanthanon" with "Lanthanum", this nouns are similar.

Lanthanon noun - Any element of the lanthanide series (atomic numbers 57 through 71).

Lanthanum and lanthanon are semantically related. You can use "Lanthanum" instead a noun "Lanthanon".