# lanthanum

> English word · Noun · IPA /ˈlænθənəm/ · frequency rank #89,538

## Definitions
1. A chemical element (symbol La) with an atomic number of 57: a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air.
2. An atom of this element.

## Etymology
From Ancient Greek λανθάνω (lanthánō, “to escape notice”) + -um (“a chemical element”), because it had gone long undetected in mineral ores.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/lanthanum