Meaning

noun any herbaceous plant having medicinal properties

noun a person lacking intelligence or common sense

adjective having few parts; not complex or complicated or involved

originInherited from Middle English symple, simple, from Old French simple, from Latin simplex (“simple”, literally “onefold”) (as opposed to duplex (“double”, literally “twofold”)), from semel (“the same”) + plicō (“to fold”). See same and fold. Compare single, singular, simultaneous, etc. Partially displaced native English onefold.

Etymology from Wiktionary, CC BY-SA 3.0