First recorded in 1375–1425.
Comes from Latin, from the past participle of inveterāre, “to grow old, allow to grow old, preserve.\"
Inveterāre contains veter-, the stem of vetus, meaning “old,\" which is also the stem of the word veteran.
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\r\nEXAMPLES OF INVETERATE\r\n

The inveterate procrastinator always left things until the last minute.
As an inveterate optimist, she always saw the bright side of every situation.

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protoporphyrin

noun

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