Fitna (or fitnah, pl. fitan; Arabic: فتن ,فتنة: "temptation, trial; sedition, civil strife, conflict") is an Arabic term that denotes concepts such as temptation, trial, sedition, civil strife, and conflict. The term encompasses a broad range of connotations, including trial, affliction, and distress. While it holds significant historical importance, the word is also widely used in modern Arabic, often without reference to its historical connotations.

A distinction can be observed between the meanings of fitna as used in Classical Arabic and its meanings as used in Modern Standard Arabic and various colloquial dialects. Given the conceptual significance of fitna in the Qur’an, its Qur’anic usage warrants separate consideration from, though in addition to, its broader lexical meaning in Classical Arabic.

In Islamic historiography, fitna specifically refers to civil wars within a Muslim polity, notably the five civil wars of the Islamic Caliphate between the 7th and 9th centuries CE starting with the First Fitna.

Arabic, in common with other Semitic languages like Hebrew, employs a system of root letters combined with vowel patterns to constitute its whole range of vocabulary. As such, identification of the root letters of any word might bring a better understanding the word's full semantic range.

Fitna has the triliteral root fā'-tā'-nūn (Arabic: ف ت ن). In addition to the feminine noun fitna, fitan, this root forms, in particular, a Form I active verb fatana, yaftinu (Arabic: فتن ، يفتن), a Form I passive verb futina, yuftanu (Arabic: فتن ، يفتن), a Form I maṣdar futūn (Arabic: فتون), a Form I active participle fātin (Arabic: فاتن), a Form I passive participle maftūn (Arabic: مفتون), and so on.

Edward William Lane, in his Arabic-English Lexicon compiled from various traditional Arabic lexicographical sources available in Cairo in the mid-19th-century, reported that "to burn" is the "primary signification" of the verb. The verb then came to be applied to the smelting of gold and silver. It was extended to mean causing one to enter into fire and into a state of punishment or affliction. Thus, one says that something caused one to enter al-fitna, i.e. trial, affliction, etc., or more generally, an affliction whereby some good or evil quality is put to the test. Lane glosses the noun fitna as meaning a trial, a probation, affliction, distress or hardship, and says that "the sum total of its meaning in the language of the Arabs" is an affliction whereby one is tried, proved or tested.

The definitions offered by Lane match those suggested by Badawi and Haleem in their dictionary of Qur'anic usage. They gloss the triliteral root as having the following meanings: "to purify gold and silver by smelting them; to burn; to put to the test, to afflict (in particular as a means of testing someone's endurance); to disrupt the peace of a community; to tempt, to seduce, to allure, to infatuate."

The meanings of fitna as found in Classical Arabic largely carry over into Modern Standard Arabic, as evidenced by the recitation of the same set of meanings in Hans Wehr's Dictionary of Modern Written Arabic.^{[original research?]} In addition, Wehr glosses the noun fitna as also meaning "charm, charmingness, attractiveness; enchantment, captivation, fascination, enticement, temptation; infatuation, intrigue; sedition, riot, discord, dissension, civil strife."