To teach someone or give them detailed information about how to do something.
From Latin 'instruere' (in- 'in' + struere 'to build'). Literally meant 'to build up' knowledge. The sense evolved from 'to furnish' to 'to teach' by the 14th century.
The Latin root 'struere' is the same root in 'construct' and 'structure'—so instruction is literally 'building up' knowledge in someone's mind, brick by brick!
Complete word intelligence in one call. Free tier — 50 lookups/day.