Relating to or having the quality of killing plants or weeds.
From 'herbicide' (herba meaning plant plus -cide meaning killing), plus the adjective suffix '-al.' Emerged in the 20th century as chemical weed control became common.
The term 'herbicidal' became widespread after WWII when military chemical research transformed into agricultural applications—Agent Orange was technically 'herbicidal,' showing how the same science can have very different uses.
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