To undermine something is to destroy it through some surreptitious means, to subvert it, and undermine is one of those words whose etymology is readily apparent by examining its constituent elements, under + mine, a reference to the military tactic of digging under the walls of a fortification in order to collapse them. But the word is first recorded in its figurative sense in the South English Legendary, a medieval collection of saint’s lives. The manuscript in which it appears was copied prior to 1325 and the particular version was written around 1280:
ȝif þe hosebonde wiste þe tyme [...] Whanne þe þeof wolde come, wake he wolde ffor to him ffounde And nolde him soffry nou3t his hous to vndermyne.
(If the husband knew the time [...] when the thief would come, he would wake to find him. And he would not suffer his house to be undermined.)
The literal sense of digging under a fortification is first recorded in a pre-1382 Wyclifite translation of the Bible, Jeremiah 51:58:
Þe wal of babilon [...] with vndermynyng shal ben vndermyned.
(The wall of Babylon [...] with undermining shall be undermined.)
The Vulgate version of this passage uses the verb suffodere, to dig under, to pierce from below. The fact that the figurative sense predates the literal means little. We just don’t have a surviving example of the literal usage that is older—when it comes to dating words from medieval manuscripts, differences of a few decades usually aren’t significant.
The simpler verb to mine also appears at about the same time. It’s first recorded c. 1330 in the sense of to dig under a fortification. The sense meaning to dig for minerals appears about a century later. This mine comes to English via the Anglo-Norman verb miner, which also carried both the military and the mineral sense. The Old French verb comes from a Celtic root meaning mineral or ore: Welsh has mwyn, Early Irish has méin, and Scottish Gaelic has mèinn. The addition of the under- prefix in English would appear to be redundant, but it was probably added to distinguish between digging under fortifications and digging for minerals.
In English, the military senses of both undermine and mine existed throughout the medieval period, but in the early seventeenth century the verb to mine ceased being used in the military sense and came to only mean to dig, to excavate.
Modern landmines and sea-mines are also from the same linguistic root. Often, once a tunnel was dug underneath a castle’s walls, explosives, or mines, would be placed in it and detonated, bringing the walls down. The “breach” in the walls of Harfleur that Shakespeare’s Henry V charged “once more into” was created by just such a mine. This sense of mine eventually evolved into any buried or submerged explosive.
Knowing the etymology of this word has one additional advantage. If you’ve ever played the old board game Stratego and wondered what the miner was doing on the battlefield, now you know.
“mine, v.,” mine, n.,” The Oxford English Dictionary, third edition, 2002.
“min(e (n.(4)),” “minen, (v.),” “underminen, (v.),” The Middle English Dictionary, 2001.
“miner1, myner,” The Anglo Norman Dictionary, 2008–12.
“undermine, v.,” The Oxford English Dictionary, second edition, 1989.
Copyright 1997-2015, by David Wilton