struct / stru

Building as piling up

The oldest sense of this root is not architecture but stacking. Its Indo-European ancestor meant to strew or spread, and the same base gave English straw — the material you spread on a floor. Latin struere kept the idea of laying things in order, and used it for brick, for battle lines and for arguments.

That breadth explains why the family is so varied. Structure is simply the Latin noun, the only member that arrived without a prefix. Construct, destroy, obstruct, instruct and instrument are all compounds, and each one names a direction in which something is piled: together, apart, in the way, into someone, into place.

The abstract branch

Instruction began as a physical metaphor and never entirely lost it. Latin instruere meant to fit out or equip — an army was instructus when it was drawn up and supplied — and only later came to mean furnishing someone with knowledge. Instrument comes from the same verb: a tool is something fitted into place for a purpose.

Institution has travelled furthest. From Latin institutum, "something set up", it came to mean an established practice, then an organisation, then the act of establishing. The sociological sense of an institution as a durable pattern of behaviour is nineteenth-century, and it is now the dominant one.

• structure — the Latin noun, unchanged in meaning since the 1400s
• construct — 1400s, build together; the noun is a nineteenth-century back-formation
• instruct — 1400s, equip, then teach
• destroy — through Old French destrure, from Latin destruere
• infrastructure — 1927, first for military installations, then for roads, power and water
• deconstruct — 1970s, from Derrida's French deconstruction, applied to texts and later to anything

Structure in the sciences

Chemistry and biology adopted the word for the arrangement of parts: a molecular structure, a protein structure, the structure of a cell. Computing then adopted the same sense for data, and gave it a family of technical terms — data structure, structured programming, structured query language, restructuring.

The most recent branch is linguistic and cultural. Structuralism in the twentieth century treated languages and societies as systems of relations rather than collections of items, and deconstruction was a reaction against it. Both are still live terms in the humanities, and both are, etymologically, exactly what they say: an arrangement of parts, and its undoing.