حيثحَيْثُ, (S, Msb, Mughnee, K,) indecl., (S, Msb,) with damm for its termination, (S, Msb, Mughnee,) as being likened to final words [such as قَبْلُ and بَعْدُ ending a proposition], (S, Mughnee,) because it does not [regularly] occur otherwise than prefixed to a proposition, (S,) for the being prefixed to a proposition is like the not being prefixed to anything, as the consequence of being prefixed, which is the sign of the gen. case, is not apparent: (Mughnee:) and حَيْثَ, (S, Mughnee, K,) also indecl., (S,) with fet-h, (S, Mughnee,) to render the pronunciation more easy, (Mughnee,) because damm with ى is deemed difficult to pronounce: (S:) and حَيْثِ, (Mughnee, K,) with kesr, accord. to the general rule observed to prevent the concurrence of two quiescent letters: (Mughnee:) and in like manner, حَوْثُ and حَوْثَ and حَوْثِ: (Mughnee, TA:) of which forms, حوث is asserted to be the original; (L;) though حَيْثُ is more chaste than حَوْثُ, and is the form used in the Kur-án: (Az and TA in art. حوث:) but some of the Arabs make حيث decl.: (Mughnee:) it is an adverbial noun of place, (S, Msb,) a vague adverbial noun of place, (L,) [signifying Where,] like حِينَ with respect to time: (S, K:) or it is a denotative of place, by general consent: but accord. to Akh it sometimes occurs as denoting time, [signifying when,] as in the following verse, (Mughnee, TA,) which is the strongest evidence of its use in this sense: (TA:)
حَيْثَمَا تَسْتَقِمْ يُقَدِّرْ لَكَ اللّٰهُ
نَجَاحًا فِى غَابِرِ الأَزْمَانِ [Whenever thou shalt pursue a right course, God will decree thee success in the time to come]: (Mughnee, TA:) but in most instances it occupies the place of an accus., as an adverbial noun of place; or of a gen., governed by مِنْ, and sometimes by another prep., as in the saying (of Zuheyr, TA in art. قشعم), لَدَى حَيْثُ أَلْقَتْ رَحْلَهَاأُمُّ قَشْعَمِ [At the place where Calamity, or Fate, has put down her saddle, i. e., made her abode]: and sometimes it occurs as an objective complement, as it is said to do in اَللّٰهُ أَعْلَمُ حَيْثُ يَجْعَلُ رِسَالَاتِهِ [in the Kur vi. 124], i. e. God is knowing: He knows where to bestow his apostolic commissions; يَعْلَمُ being suppressed, as implied by أَعْلَمُ; or أَعْلَمُ may be rendered by عَالِمٌ, and so may govern the accus. case. (Mughnee.) Accord. to rule, (Mughnee,) in every instance, (S, Mughnee,) it is prefixed to a proposition, (S, Msb, Mughnee,) nominal, or verbal, but in most cases the latter; (Mughnee;) as in أَقُومُ حَيْثُ يَقُومُ زَيْدٌ [I will stand where Zeyd shall stand]; and حَيْثُ تَكُونُ أَكُونُ [Where thou shalt be, I will be]; (S;) and جَلَسْتُ حَيْثُ زَيْدًا أَرَاهُ [I sat where I saw Zeyd], the accus. case being preferred in an instance like this; (Mughnee;) and اذْهَبْ حَيْثُ شئْتَ [Go thou whither thou wilt.] (Msb in art. حَين.) Youshould not say حَيْثُ زَيْدٌ [alone]: (S:) or it occurs prefixed to a single word in poetry; (Msb, Mughnee;) as in the saying, وَنَطْعُنُهُمْ تَحْتَ الكُلَى بَعْدَ ضَرْبِهِمْ
بِبِيضِ المَوَاضِى حَيْثُ لَىِّ العَمَائِمِ [And we pierce them beneath the kidneys, after smiting them, with the sharp swords, where the turbans are wound]; (Mughnee;) but this is irregular; (Msb, Mughnee;) though Ks holds it to be regular. (Mughnee.) Lh relates, on the authority of Ks, that some make حيث to govern a noun in the gen. case, as in the saying, أَمَا تَرَى حَيْثُ سُهَيْلٍ طَالِعَا [Seest thou not where Canopus is, rising?]: but he says that this is not of respectable authority: (L:) some write حَيْثَ سُهَيْلٍ: and some, حَيْثُ سُهَيْلٌ, [which is the common reading, سهيل being an inchoative, and] the enunciative, مَوْجُودٌ, being suppressed. (Mughnee.) Abu-l-Fet-h says that he who prefixes حيث to a single word makes it declinable. (Mughnee.) [Accord. to Fei,] BenooTemeem say حَيْثَ when it occupies the place of an accus., as in the phrase, قُمْ حَيْثَ يَقُومُ زَيْدٌ [Stand thou where Zeyd shall stand]. (Msb.) Ks says, I have heard among Benoo-Temeem, of Benoo-Yarbooa and Tuheiyeh, those who say حَيْثَ in every case, when it occupies the place of a gen., and that of an accus., and that of a nom.; saying مِنْ حَيْثَ لَايَعْلَمُونَ [Whence they know not], and حَيْثَ الْتَقَيْنَا [Where we met]: and he says also, I have heard some of Benu-l-HárithIbn-Asad-Ibn-El-Hárith-Ibn-Thaalabeh, and all Benoo-Fak'as, say حَيْثِ when it occupies the place of a gen., and حَيْثَ when it occupies the place of an accus.; saying مِنْ حَيْثِ لَا يَعْلَمُونَ, and حَيْثَ الْتَقَيْنَا. (L.) Sometimes the proposition after حيث commences with إِنَّ, as in اِجْلِسْ حَيْثُ إِنَّ زَيْدًا جَالِسٌ [Sit thou where Zeyd is sitting]. (K in art. أن, and IAk p. 92.) b2:  It sometimes comprises the meanings of two adverbial nouns of place, as when you say, حَيْثُ عَبْدُ اللّٰهِ قَاعِدٌ زَيْدٌ قَائِمٌ [Where' Abd-Allah is sitting, there Zeyd is standing]. (AHeyth, L.) b3:  The restrictive مَا (مَا كَافَّةٌ) is sometimes affixed to it, and in this case it implies a conditional meaning, [signifying Wherever, or wheresoever, and, accord. to Akh, whenever, or whensoever,] (Mughnee, TA,) and renders two verbs mejzoom, (Mughnee,) as in the saying, حَيْثُمَا تَجْلِسْ أَجْلِسْ [Wherever thou shalt sit, I will sit], (S,) and in the first of the verses cited above: (Mughnee, TA:) it is not [properly, though it is sometimes improperly,] used as a conditional without ما. (S.) b4:  [It is also used, in scientific and other post-classical works, in senses different from those explained above. Thus, مِنْ حَيْثُ is used to signify As to, or in respect of: so in the phrase مِنْ حَيْثُ اللَّفْظِ وَالمَعْنَىAs to, or in respect of, the word and the meaning. Also As, or considered as, absolutely, or abstractedly: so in the phrase مِنْ حَيْثُ هُوَ, or مِنْ حَيْثُ هُوَ هُوَ, As, or considered as, such, absolutely, or abstractedly; and الإِنْسَانُ مِنْ حَيْثُ هُوَإِنْسَانٌ Man, as, or considered as, man, absolutely, or abstractedly. And As, meaning considered merely or only or simply as: so in the saying, الإِنْسَانُ مِنْ حَيْثُ إِنَّهُ يَصِحُّ وَتَزُولُ عَنْهُ السِّحَّةُ مَوْضُوعُ الطِّبِّ Man, as, or considered merely or only or simply as, being healthy and ceasing to be healthy, is the object of therapeutics. And As, meaning since, or because: so in the saying, النَّارُ مِنْ حَيْثُ إِنَّهَا حَارَّةٌ تُسَخِّنُ المَآءَ Fire, as, or since, or because, it is hot, heats water. بِحَيْثُ is also vulgarly used in this sense. And correctly as meaning So that; so as that; in such a state, or condition, that: often syn. with حَتَّى.]