Flourish derives from Old French 'florir' (to flower), from Latin 'flōrēre,' carrying the metaphor of blooming into the meaning of thriving.
To grow or develop in a healthy or vigorous way; to thrive. As a noun, a bold or extravagant gesture or action; an ornamental embellishment.
From Old French "floriss-," the lengthened stem of "florir" ("to blossom, to flower"), from Vulgar Latin *flōrīre, a reorganization of classical Latin "flōrēre" ("to bloom, to prosper"). The Latin verb derives from "flōs" (genitive "flōris," "flower"), tracing to Proto-Indo-European *bʰleh₃- ("to bloom, to thrive"). This PIE root is one of the most productive in the botanical vocabulary of Indo-European languages: it yielded Proto-Germanic