Past tense of encroach; moved gradually or stealthily into territory or space that belongs to someone else.
From en- + croach (from Old French crochier, meaning to hook or seize). The metaphor is of 'hooking' or gradually pulling oneself into others' territory.
Encroachment happens so gradually that people often don't notice—sea levels encroach on coastlines, deserts encroach on forests, and neighbors' fences encroach on property lines so slowly that only old photos reveal the change!
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