This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2009)

Fluctuat nec mergitur (or FLVCTVAT·NEC·MERGITVR in Roman-style inscriptions) is a Latin phrase meaning "She is tossed by the waves, but is not sunk":

• fluctuat: the verb fluctuāre in the third-person indicative singular of the present tense in the active voice. Fluctuāre means "to be wave-like", "move up and down"; of persons and passions, "to be tossed about", "to waver". In English the verb fluctuāre gave to fluctuate. The subject is not explicitly expressed, and can be inferred to be "he", "she" or "it". "She" is used in the English translation because ships and cities are traditionally regarded as feminine.
• nec: contraction of neque, which is equivalent to et nōn, meaning "and not", "and does not", "and is not".
• mergitur: the verb mergere in the third-person indicative singular of the present tense in the passive voice. Mergere means "to dip", "plunge into liquid", "immerse", "sink", "overwhelm". In English the verb mergere gave to merge as well as to submerge (literally "merge under", "sub-merge").

[edit] Uses

This phrase is the motto of Paris, France, and is present in the city coat of arms depicting a ship floating on a rough sea. Both motto and city arms have their origins in the river Seine boatsman's corporation; this powerful hanse ruled the city's trade and commerce as early as the Roman era.^{[citation needed]} Although this corporation through the centuries became an entity resembling more a municipal government than a trade organization, they maintained their original arms and motto, and it is for this that the Mairie de Paris bears them still today.

The phrase is used in "Les Copains d'abord" by the French singer/poet Georges Brassens. It is also the motto of Albert Messiah's classic textbook on quantum mechanics.