From Proto-Indo-European *yós, *yéh₂, *yód (“who, which”). Cognates include Ancient Greek ὅς (hós), ἥ (hḗ), ὅ (hó), Avestan 𐬫𐬋 (yō), Phrygian ιος (yos) and Old Church Slavonic иже (i-že), Lithuanian jis, ji.
यद् • (yád)
|Nominative||यः (yaḥ)||या (yā)||यत् (yat)||यौ (yau)||ये (ye)||ये (ye)||ये (ye)||याः (yāḥ)||यानि (yāni)|
|Accusative||यम् (yam)||याम् (yām)||यत् (yat)||यौ (yau)||ये (ye)||ये (ye)||यान् (yān)||याः (yāḥ)||यानि (yāni)|
|Instrumental||येन (yena)||यया(yayā)||येन (yena)||याभ्याम् (yābhyām)||याभ्याम् (yābhyām)||याभ्याम् (yābhyām)||यैः (yaiḥ)||याभिः (yābhiḥ)||यैः (yaiḥ)|
|Dative||यस्मै (yasmai)||यस्यै (yasyai)||यस्मै (yasmai)||याभ्याम् (yābhyām)||याभ्याम् (yābhyām)||याभ्याम् (yābhyām)||येभ्यः (yebhyaḥ)||याभ्यः (yābhyaḥ)||येभ्यः (yebhyaḥ)|
|Ablative||यस्मात् (yasmāt)||यस्याः (yasyāḥ)||यस्मात् (yasmāt)||याभ्याम् (yābhyām)||याभ्याम् (yābhyām)||याभ्याम् (yābhyām)||येभ्यः (yebhyaḥ)||याभ्यः (yābhyaḥ)||येभ्यः (yebhyaḥ)|
|Genitive||यस्य (yasya)||यस्याः (yasyāḥ)||यस्य (yasya)||ययोः (yayoḥ)||ययोः (yayoḥ)||ययोः (yayoḥ)||येषाम् (yeṣām)||यासाम् (yāsām)||येषाम् (yeṣām)|
|Locative||यस्मिन् (yasmin)||यस्याम् (yasyām)||यस्मिन् (yasmin)||ययोः (yayoḥ)||ययोः (yayoḥ)||ययोः (yayoḥ)||येषु (yeṣu)||यासु (yāsu)||येषु (yeṣu)|
Usually with correlatives तद् (tad), त्यद् (tyad), एतद् (etad), इदम् (idam), अदस् (adas), तद् एतद् (tad etad), एतद् त्यद् (etad tyad), इदं तद् (idaṃ tad), तद् इदम् (tad idam), तादृश (tādṛśa), ईदृश (īdṛśa), ईदृश् (īdṛś), एतावद् (etāvad), by which it is oftener followed than preceded, or the correlative is dropped e.g.
- yas tu nā*rabhate karma kṣipram bhavati nirdravyaḥ - [he] indeed who does not begin work soon becomes poor (R.)
or the relative pronoun is dropped e.g.
- andhakam bhartāraṃ na tyajet sā mahā-satī - she who does not desert a blind husband is a very faithful wife (Vet.)
yad is often repeated to express "whoever", "whatever", "whichever", e.g.
- yo yaḥ - whatever man
- yā yā - whatever woman
- yo yaj jayati tasya tat - whatever he wins (in war) belongs to him (Mn. VII, 96)
- yad yad vadati tad tad bhavati - whatever he says is true
- upyate yad dhi yad bījam tat tad eva prarohati - whatever seed is sown, that even comes forth (Mn. IX, 40)
Similar indefinite meanings are expressed by the relative joined with तद् (tad) e.g.
- yasmai tasmai - to any one whatever
- yadvā tadvā - anything whatever
- yaḥ kaścit - whosoever
- yāni kāni ca mitrāṇi - any friends whatsoever
- yena kenā*py upā*yena - by any means whatsoever
yad is joined with त्वद् (tvad) to express generalization e.g.
- śūdrāṃs tvad yāṃs tvad - either the śūdras or anybody else (ŚBr.)
or immediately followed by a personal pronoun on which it lays emphasis e.g.
- yo 'ham - I that very person who
- yas tvaṃ kathaṃ vettha - how do you know? (ŚBr.)
It is also used in the sense of "si quis" e.g.
- striyaṃ spṛśed yaḥ - should any one touch a woman
yad is also used without the copula e.g.
- andho jaḍaḥ pīṭha sarpī saptatyā sthaviraśca yaḥ - a blind man, an idiot, a cripple, and a man seventy years old (Mn. VIII, 394)
Sometimes there is a change of construction in such cases e.g ye ca mānuṣāḥ for mānuṣāṃś-ca (Mn. X, 86).
The nominative singular neuter yad is then often used without regard to gender or number and may be translated by "as regards", "as for", e.g.
- kṣatraṃ vā etad vanaspatīnāṃ yan nyag-rodhaḥ - as for the nyag-rodha, it is certainly the prince among trees (AitBr.)
or by "that is to say", "to wit" e.g.
- tato devā etaṃ vajraṃ dadṛśur yad apaḥ - the gods then saw this thunderbolt, to wit, the water (ŚBr.)
yad as an adverbial conjunction generally means "that", especially after verbs of saying, thinking etc., often introducing an oratio directa with or without इति (iti); iti yad, at the end of a sentence = "thinking that", "under the impression that" e.g. Ratnāv. ii, 2÷8.
yad can also mean "so that", "in order that", "wherefore", "whence", "as", "in as much as", "since", "because" (the correlative being तद् (tad), "therefore"), "when", "if" RV. etc.
- ádha yád - even if, although (RV.)
- yad api - id. (Megh.
- yad u - evam - as - so (ŚvetUp.)
- yad uta - that (Bālar.), that is to say, scilicet (Kāraṇḍ., DivyĀv.)
- yat kila - that (Prasannar.)
- yac ca - if, that is to say (Car.)
- yac ca-yac ca - both - and (DivyĀv.); that
According to Pāṇ.. 3-3, 148 after expressions of "impossibility", "disbelief", "hope", "disregard", "reproach" and, "wonder":
- yad vā - or else (often found in commentators), whether (Kāv., Rājat.), however (Bālar.)
- yad vā - yadi vā - if-or it (Bhag.)
- yad bhūyasā - for the most part (DivyĀv.)
- yat satyam - certainly, indeed, of course (Mṛicch., Ratnāv.)
- yan nu, with 1st person - what if I, let me (DivyĀv.)