Complex means having many different and connected parts, making something not simple to understand or deal with. As a noun, it can mean a group of related buildings or a set of related ideas and feelings.
From Latin *complexus* “embraced, entwined,” from *com-* “together” + *plectere* “to braid, twine.” The image is of many strands woven together.
Something complex isn’t just ‘complicated for no reason’; it’s many simple parts interacting at once. A forest, a city, and your own personality are all complexes of tiny pieces whose relationships matter more than the pieces themselves.
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