Interlocked Etymologies

The etymologies of the words lock and castle in many languages seem curiously—interlocked. Despite their seemingly distinct meanings, they share a thread of linguistic history that connects them in a fascinating way. Let’s break it down:

The journey begins in Middle Latin, where we find the word clūsa, which originally referred to a monk’s cell or a narrow valley. This word comes from claudere, meaning ‘to close’ or ‘shut in’. From this, the concept of enclosure, closure, and confinement emerges, leading us to the next stop in our etymological tour.

In Middle High German, this Latin term was calqued (literally translated) into the word sloʒ, which could mean both a ‘fortified building’ or ‘castle’, as well as a ‘lock’ or ‘bolt’. The verb slieʒen, meaning ‘to close’ or ‘shut in’, is clearly tied to both these senses—sealing things off, whether it’s a building or a door.

This same pattern was passed on to the Slavic languages. In Czech, zámek can mean both ‘castle’ and ‘lock’. The meaning ‘castle’ is likely calqued from the German sloʒ, while the form meaning ‘lock’ derives from a native root like the verb za-mknout.

Via Polish, this connection traveled eastward, so in Russian, we find two forms of the word замок—one for a ‘castle’, and the other for a ‘lock’ (замо́к). The two forms differ by stress: the version stressed on the final syllable (замо́к ‘lock’) is the original East Slavic form, while the version with penultimate stress (за́мок ‘castle’) likely came from Polish, where it follows the same stress pattern and has the calqued meaning of ‘castle’.

In each case, the metaphor of something being ‘shut in’, whether it’s a castle or a lock, remains central. The physical idea of securing a space ties these meanings together, creating a link between a secure, enclosed building and the device used to close it.

(Interestingly, English shares some of this entanglement. The word slot—cognate with the German Schloss meaning both ‘lock’ and ‘castle’—is semantically related to German Loch ‘hole, slot’. This connects directly with the English lock, as well as with related terms in other languages, such as French loquet and Italian lucchetto, all of which deal with the concept of closure, fastening, or securing.)