Arabic verbs are based on a ‘root’ consisting of consonants (usually three, sometimes four or more) that are placed in different patterns depending on the conjugation. For example, the root ك ت ب can be conjugated as أَكْتُبُ 'I write’, تَكْتُبُونَ 'you (pl.) write’, كُتِبَ 'It was written’, et cetera.
Groups of verbs with roughly similar conjugation patterns are known as forms (الأوزان awzan in Arabic). For example, form I contains verbs that conjugate like ضَرَبَ, دَرَسَ, كَتَبَ while form III contains verbs that conjugate like عَامَلَ, سَافَرَ, كَاتَبَ. Sometimes verb forms reflect an aspect of the verb’s meaning; for example, form II is often used for causatives (e.g. دَرَّسَ ‘to teach’, وَقَّفَ ‘to bring to a stop’) and form VII is often used for reciprocals (e.g. تَكَاتَبَ 'to correspond (with each other)’, تَفَارَقَ 'to separate (from each other)’). In total there are fifteen verb forms in Arabic, but only the first ten forms are in common use.
Within each verb form, verbs may conjugate differently depending on the consonants in their root. For example, there are some differences in the conjugation of roots containing the consonants ي، و، ء (e.g. the verb قَالَ ‘say’ from the root ق و ل ), roots ending in a doubled consonant (e.g. حَبَّ ‘love’ from the root ح ب ب ), and in roots containing four or more consonants (e.g. تَرْجَمَ ‘translate’ from the root ت ر ج م ). In the Reverso Conjugator, verbs within a single form that conjugate similarly are grouped together in a verb model. For example, in form I the verbs رَاحَ, مَاتَ, دَارَ, قَالَ are in the same verb model because they conjugate according to the same pattern, all having a medial و in their root.
Arabic verbs conjugate for two tenses: past and present, for example قَرَأَ 'he read’, يَقْرَأُ 'he reads’. Future tense is expressed by adding the prefix سَـ or the word سوف before the verb; so سيقرأ or سوف يقرأ 'he will read’.
There is no infinitive form in Arabic (like English ‘to see’, French ‘voir’, Hebrew לראות ). Instead, the convention is to use the 3rd person male past form as the verb’s citation form, since it is the simplest form of the verb. For example, قَرَأَ 'he read’ will appear in Reverso Conjugator as the base form of the verb ‘to read’ in Arabic.
Arabic verbs have an imperative form for expressing commands. For example, اِقْرَأْ 'read! (ms.)’ This is only used for positive commands; negative commands are instead formed by لا + jussive, for example لَا تَقْرَأْ 'don’t read! (ms.)’
In addition to the indicative (past and present) and imperative moods, Arabic verbs also can be conjugated for the subjunctive and jussive moods. The subjunctive is used after some subordinating conjunctions and other particles, e.g. تُرِيدُ أَنْ تَقْرَأَ 'you want to read’. It also is used to form the negative future after the particle لَنْ , as in لَنْ تَقْرَأَ 'you will not read’.
The jussive is used after the particle لم to form the negative past, e.g. لَمْ تَقْرَأْ 'you did not read’. It is also used for negative commands as mentioned above, and after some particles including the conditional particles إنْ ‘if’ and إِذَا 'if’.
Arabic verbs conjugate for person, number, and gender, though gender is not distinguished in the first person (أَحْكِي 'I speak (m. or f.)’, نَحْكِي 'we speak (m. or f.)’). In addition to singular and plural number, verbs also have separate conjugation for dual number (‘two of us’, ‘you two’, ‘two of them’); dual conjugations are displayed in Reverso Conjugator in parentheses with their corresponding dual pronouns.
Imperatives only exist for second person but conjugate for number and gender, so اِحْكِ 'speak! (ms.)’ اِحْكِي 'speak! (fs.)’, اِحْكُوا 'speak! (mp.)’, اِحْكِينَ 'speak! (fp.)’
Participles and the verbal noun do not inflect for person, number, or gender.
Verbs in Arabic have two participle forms: the active participle and the passive participle. For example, the verb عَلَّمَ ‘teach’ has active participle مُعَلِّم ''teaching’ and passive participle مُعَلَّم 'be taught’. Verbs in Arabic also have a verbal noun which refers to the action described by the verb; in this case تَعْلِيم '(the act of) teaching’.
Arabic verbs can be conjugated for passive voice by a change in vocalization, as in كَسَرَ 'he broke’, كُسِرَ 'it (he) was broken’. Passive forms exist for indicative (past and present), subjunctive, and jussive verbs.