The word mesa entered English from Spanish, where it simply means table. Spanish explorers crossing the arid landscapes of the American Southwest saw flat-topped mountains rising from the desert floor and called them what they looked like: tables. The metaphor was so natural and so apt that mesa became the standard English geological term for this landform, displacing any Anglo-Saxon alternative.
Spanish mesa derives from Latin mensa (table), a word of uncertain deeper etymology — it may be related to an Oscan or pre-Latin Italic root. The Latin mensa produced table-related words across the Romance languages: Italian mensa (table, canteen), Portuguese mesa (table), and Romanian masă (table).
Geologically, a mesa forms through differential erosion. A layer of hard, erosion-resistant rock — typically volcanic basite, sandstone, or limestone — caps a body of softer rock. Over millions of years, the softer rock erodes away around the edges, leaving a flat-topped remnant capped by the resistant layer. As erosion continues, a mesa may shrink into a butte (a smaller flat-topped remnant) and eventually into a pinnacle or spire.
The relationship between mesa and butte is one of scale: a mesa is wider than it is tall, while a butte is taller than it is wide. Both terms come from Spanish and French respectively, reflecting the dual colonial heritage of the American West — Spanish in the Southwest, French in the northern plains and Mississippi valley.
The most famous mesa landscapes in the world are found in the Colorado Plateau region of the American Southwest — Monument Valley, Mesa Verde, and the Grand Staircase-Escalante. Mesa Verde, literally 'green table,' was named for its juniper-and-piñon-covered flat top, which contrasts dramatically with the surrounding desert. The mesa shelters some of the most important Ancestral Puebloan cliff dwellings in North America, built in alcoves beneath the mesa's rimrock.
In modern usage, Mesa has become a common place name across the American Southwest. Mesa, Arizona — the state's third-largest city with over 500,000 residents — sits on a mesa above the Salt River Valley. The word has also entered technical vocabulary in electronics, where a mesa transistor has a flat-topped structure created by etching away surrounding material.