In linguistics the benefactive is a case that marks the beneficiary of an action. It is expressed in English with the preposition 'for', as in 'I bought flowers for my mother', or 'It is good (or bad) for you', or 'water for the horse'.

In languages with only a small number of cases it might be expressed by the dative, the case equivalent to 'to' in 'I gave flowers to my mother'. In languages with more complex case morphology the two cases may be distinct. For example, in Basque:

    ama-rentzat lore-ak   eros-i    ditut
    mother-BEN  flower-PL buy-PERF  AUX
    I bought flowers for (my) mother.

    ama-ri      lore-ak   eman      dizkiot
    mother-DAT  flower-PL give:PERF AUX
    I gave flowers to mother.
This is not just a semantic distinction between 'give' and 'buy', since the dative can also be used with 'buy'. Presumably the difference is that with the dative Amari loreak erosi dizkiot 'I bought flowers for mother' the implication is that she actually got them. This would be consistent with other subtleties in Basque cases, which distinguish motion to, towards, and up to a place.

(In Basque the auxiliary is morphologically very complex, and the two AUX words given here include marking for subject 'I', object 'they', and in the second sentence indirect object 'to her'. The literal gloss in the second line is for the benefit of linguists, but it's too complicated to break down the gloss of the AUX.)

The term 'benefactive' is used quite a lot for this sort of semantic case role, even if a language has no precise way of setting it off from other roles. In English 'for' has several related senses, another of which is purpose, as in 'The books are for my work'. It is not obvious that these are distinct in English, but in Basque a different case, called destinative (it could also be called purposive) is used for this sense of 'for'. Essentially, animate nouns are beneficiaries and take the benefactive, while inanimate purposes take the destinative:

    liburu-ak nire lan-erako dira
    book-PL   my   work-DEST AUX
    The books are for my work.
This covers the meaning of 'benefactive', but while we're on the endlessly fascinating Basque I have to add some more details about its benefactive case. A number of case forms are composed of several elements, and the benefactive -(r)entzat consists of the genitive ending -(r)en followed by the essive ending -tzat. The essive (or translative or prolative) by itself says the noun is fulfilling a function: He used it as a hammer; He considers him his son; He wants her for a wife.

The destinative is also compound: it consists of the allative -(e)ra 'to' and an adjectivalizing suffix -ko. This -ko is widespread and hard to explain in simple terms. It also turns up on the benefactive when the case form is being used as an adjective in a noun phrase. Compare:

    ama-rentzat lore-ak   eros-i    ditut
    mother-BEN  flower-PL buy-PERF  AUX
    I bought flowers for mother.

    ama-rentza-ko  lore-ak   gorri-ak dira
    mother-BEN-ADJ flower-PL red-PL   AUX
    The flowers for mother are red.
In the first sentence, 'flowers for mother' doesn't form a single constituent, but 'flowers' and 'for mother' are two separate slots governed by the verb 'buy'. In the second sentence they are now one constituent, and 'are red' is being predicated of them. Since the destinative case already contains the -ko ending, this distinction doesn't apply there, and you say nire lanerako liburuak 'the books for my work'.

Anyone who knows Basque and can spot errors in my auxiliaries is welcome to pipe up.

Saltarelli, M. (1988) Basque, Croom Helm
Trask, R.L. (1997) The History of Basque, Routledge