In this lesson: Master struct/stru (build, pile up) — building theories (construct), rebuilding the past (reconstruct), building blockades (obstruct), and the tools you build with (instrument).
About This Root
The root struct comes from Latin struere, meaning "to pile up, to build, to arrange in layers." Its past participle was structus — which is where the English spelling struct comes from. Picture a Roman builder stacking stone on stone, course by course: that physical act of layering things into a stable whole is the seed of every struct word.
The most literal survivors are easy to read. structure is simply "the thing that has been built" — the arrangement of stacked parts, whether a building, a sentence, or an organization. construct adds con- (together): to pile parts together into a whole. construction is the act or result of that piling. And infrastructure literally means the structure beneath (Latin infra- "below") — the stacked foundations (roads, power, water) that everything else is built on top of.
From "build" the root branches in three directions, each chosen by its prefix:
- Build up. con- + struere → construct / construction / reconstruct (build again).
- Build into the mind. in- (into) + struere → instruct: to "build something into" a learner — to teach. The picture is of stacking knowledge into someone, brick by brick. From the same idea comes instruction (the teaching, or the order), instructor (the one who builds knowledge into you), and instructive (something that builds your understanding). A famous offshoot is instrument: a tool you build with — Latin instrumentum meant "equipment, apparatus." That's why a hammer, a violin, and a measuring gauge are all "instruments": each is a built tool for getting something done. instrumental then means "serving as the tool that made something happen."
- Tear down what was built. de- (down, reversal) + struere → destroy / destruction / destructive: to un-build, to take the stack apart. Notice the surprise: the verb is destroy (worn down through Old French destruire), but the noun keeps the Latin spelling destruction — same root, two spellings.
- Pile something in the way. ob- (against, in the path of) + struere → obstruct / obstruction: to build a barrier across someone's path, to block.
One quiet outlier is construe (con- + struere): originally "to arrange the words of a sentence in order so as to parse it" — i.e. to build the meaning. It came in through grammar lessons and now means "to interpret."
The pattern to carry away: struct is always about a built arrangement of parts. The prefix tells you the direction of the building — con- together, in- into the mind, de- down/undo, ob- across the path, infra- underneath.
Think of a builder stacking bricks: every struct word is about a stack of parts. con-struct stacks them together, de-stroy knocks the stack down, in-struct stacks knowledge into your head, ob-struct stacks a wall across your path.
Focus words· 7
con- (together) + struct (build) = to pile parts together into a whole. The verb covers both physical building (construct a bridge) and abstract building (construct an argument). The noun construct names something the mind builds — "race is a social construct" means it's assembled by society, not found in nature.
Workers will construct the new stadium over the next two years.
The lawyer carefully constructed her argument.
To block or hinder progress or movement
ob- (against, in the path of) + struere (build) = to build a barrier across someone's way. The image is a pile of rubble blocking a road. This explains "obstruction of justice" — you're not destroying justice, you're piling obstacles in its path so it can't move forward.
In construct and instruct, the root struct means…
in- (into) + struct (build) = "to build into." To instruct is to stack knowledge into a learner's mind, layer by layer like a builder. The same "building in" gives the second sense: to instruct someone to act is to set a directive firmly into place.
The least obvious member. in- (into) + struere (build) = "to build into." To instruct someone is to stack knowledge into their mind, layer by layer, like a builder laying courses of brick. That's why teaching, training, and giving orders all share this word — each "builds something into" the listener.
He instructed the new recruits in safety procedures.
The judge instructed the jury to ignore the remark.
ob- (across the way) + struct → "to build a barrier across a path." Which word?
Playing a key role in achieving something; a piece of music without vocals
Extended family · 11 words
See the root page for the full family.
Coach note
To instruct is to build knowledge into someone; an instrument is what a task is equipped — built out — with, so being instrumental in a discovery means serving as its key tool. The subtle one is construe (con + strue): to pile the pieces of a text together and read out a meaning — TOEFL passages love "was construed as." Keep struct apart from its neighbor st: an obstruction is built across the road; an obstacle merely stands there. Bonus cousin: architect = Greek archi (chief) + tekton (builder).
Related Roots
Both relate to making, but fac/fact (from facere) means "to make/do" in the broadest sense — manufacture, factory, fact. struct is narrower: it means to make by piling parts into an arrangement — a structure, not just any product. Quick test: assembling parts into a built whole → struct; making or doing in general → fac.
architect = archi- (chief) + tekton (builder), from Greek for one who builds. tect came through Greek, while struct came through Latin, but both end up meaning "build," so an architect designs a structure.
Practice
What does the root struct/stru mean?