You’ve probably already encountered the idea of the causative (make someone do something) in fuSHa with reference to forms II (fa33ala) and IV (2af3ala) of the verb. In many ways causatives work similarly in fuSHa and in colloquial, but the structures are a bit different and causatives are perhaps more common in dialect.
Unlike English, which distinguishes compulsorily between ‘make’ and ‘let’ (both kinds of causative), Arabic combines the two under one basic causative. The causative can be formed with خلّى khalla plus a verb or with an independent verb form – both can mean either ‘let X do’ or ‘make X do’, or related meanings.
Khalla ykhalli is probably derived from the fuSHa for ‘to empty’, but it is used in the sense of ‘allow’ or ‘make’. It is combined with an object and a verb conjugated in the b-less present, quite simply:
خليتو يفوت khalleeto yfuut ‘I made him go in’, ‘I let him go in’.
خلاني اقرا khallaani é2ra ‘he made me read’, ‘he let me read’
خلوني روح khalluuni ruu7 ‘let me go!’
It can also be used in a way that is not a command but expresses a suggestion, similar to English ‘let’s’:
خلينا نجرب khalliina njarreb ‘let’s give it a go’
It can also mean ‘leave’ or ‘keep’:
خليا معك khalliyya ma3ak ‘keep it with you’
Relatedly, it can mean ‘stay’, ‘keep on’ etc, in which case the singular masculine imperative is combined with pronouns indicating the subject:
خليك دغري khalliik déghri – (you) keep going straight on
خليكون هون khalliikon hoon – (all of you) stay here
There are a few other similar constructions which distinguish between ‘making’ and ‘letting’ or have other implications. Their syntax is generally the same:
تركو يمشي tréko yémshi ‘let him go’ (= leave him to go)
جبرني ايجي jabarni iiji ‘he forced me to come’
Derived verbal forms
Form IV does not really exist in Shami. Some common form IVs have been reanalysed as quadrilateral verbs (اسلم يئسلم aslam y2aslem ‘convert to Islam’), others as form I (علن يعلن ‘announce’), one even as form III (آمن يئامن aaman y2aamen ‘believe’). A few verbs do act like form IV, with an a- in the past tense that disappears in the present, but these are probably recent reborrowings from fuSHa. But Form II is the only productive way of forming causatives, and it is very common (although by no means are all form IIs causative).
Form IIs often have a bewildering number of possible idiomatic English translations. Most have an underlying/equivalent non-causative verb, usually either form I or form V:
فوّت fawwat ‘let in’, ‘put in’, ‘take inside’ etc < فات faat ‘enter’ (this is also used in the sense of ‘miss out on’, ‘let something slip from between your fingers’ – the causative of the fuSHa verb faat which is rarely used in colloquial)
سمّك sammak ‘make thicker, thicken, make wider’ etc < سمك sémek ‘get thicker’
خفّف khaffaf ‘lighten, go lighter on, reduce’ etc < خفّ khaff ‘get lighter’
مشّى mashsha ‘walk [a dog], make walk, make move, let move, let pass’ etc < مشي méshi ‘walk, move’
فيّق fayya2 ‘wake [someone] up’ < فاق faa2 ‘wake up’
غيّر ghayyar ‘change’ (transitive) < تغيّر tghayyar ‘change’ (intransitive – this one can also have a passive meaning ‘be changed/be changeable’, as in التيكيت ما بيتغيّر ‘the ticket can’t be changed’)
جوّز jawwaz ‘marry off, marry (i.e. be the presiding official, religious figure etc at a marriage ceremony)’ (transitive) < تجوز tjawwaz ‘get married’
Quite a lot of these forms have, either alongside or instead of their predictable meanings, more specific or idiomatic meanings:
درّس darras ‘put through school, send to school’, ‘teach’
رقّص ra22aS ‘dance with, get to dance’
لعّب la33ab ‘play with’
سمّع samma3 ‘let/make hear’, ‘put on [a song]’
تقّل ta22al ‘make heavier’, ‘overdo it’
One common causative-esque use of form II which is not quite the same is to derive verbs meaning ‘to apply a substance’:
دهّب dahhab ‘gild’ (i.e. apply gold to) < دهب dahab ‘gold’
زيّت zayyat ‘oil’ < زيت zeet ‘oil’
Another occasional causative-like usage which you might come across (although it is more common in form X verbs with ista-) is to derive verbs from adjectives meaning ‘consider something X’:
كذّب kazzab ‘disbelieve’ (i.e. ‘consider lies/a liar’)
صدق sadda2 ‘believe’ (i.e. ‘consider true/honest’)
Occasionally they also have other meanings entirely you should be aware of:
سكّر sakkar ‘get/make someone drunk’ (< séker ‘get drunk’), ‘close’ (no underlying verb)
Finally, there are a few form II verbs that can be both causatives and synonyms of their underlying verb: وقّف wa22af (intransitive ‘stop, stand’ or transitive ‘stop, make stand’) and وصل waSSal (intransitive ‘arrive’ or causative ‘deliver, make arrive’) for example. Watch out for these.
Syntax of causatives is pretty predictable. The subject of the underlying verb becomes its object, and the object of the underlying verb – if there is one – stays as a second object.
سمع الغنية séme3 élghanniyye ‘he listened to the song’ > سمّعتو الغنية samma3to lghanniyye ‘I played him the song’
غلت المي ghalet élmoyy ‘the water boiled’ > غلّيت المي ghalleet élmoyy ‘I boiled the water’
As with other double object verbs, when both objects are a preposition the carrier yaa- is used:
سمّعتو ياها samma3to yaaha ‘I played it to him’
If the underlying verb takes a preposition, this usually stays:
فهم عليها féhem 3aleeha ‘he understood her’ > فهّمتو عليها fahhamto 3aleeha ‘I made him understand her’ (I explained what she was saying to him)
فات ع المكتب faat 3almaktab ‘he went into the office’ > فوّتّو ع المكتب fawwatto 3almaktab ‘I took him into the office’
Not all form IIs are causatives. Some are verbs of becoming (شوّب shawwab ‘become hot’). Some, related to causatives, are verbs of ‘application’ derived from a substance (دهّب dahhab ‘gild’, جلّد jallad ‘bind [a book]’). Some are common or less common synonyms of a form I verb, sometimes used in different contexts (غسّل ghassal, ‘wash [body parts]’ and غسل ghasal ‘wash [clothes]’, فكّك fakkak and فكّ fakk ‘take apart’). Some mean ‘spend [a specific time]’: مسّى massa ‘spend an evening’, صيّف Sayyaf ‘to summer’. And some are just verbs with no clear derivational meaning (فكّر fakkar).