Some people believe Ishq (Arabic: عشق, ‘išq) is an Arabic word meaning "love" or "passion", also widely used in other languages of the Muslim world. Many people think that išq (newer pronunciation ešq) is a loanword from Arabic but it's wrong. This word has an Avestan root, iška and has been išk in Middle Persian. It also mentions Indo-European cognates for this word.
iška is a compound from -iš which means "to want, to desire, to seek" and suffix -ka. the PIE of -iš is apparently -ais. Avestan iš- is cognate with Sanskrit eṣ- "to wish, strive for, seek", icchā- "wish, desire", icchati "seeks for, wishes", iṣta- "beloved, sought", iṣti- "search, desire", Pali icchaka- "wishing, desirous". Note also that this word exists in Middle Persian in the form of išt "desire", as attested by Farahvaši.
The Avestan and Sanskrit words come from the Proto-Indo-European base *ais- "to wish, desire", *aisskā- "desire, search", which have several offshoots in other Indo-European languages: Old Church Slavic isko, išto "to seek, desire"; iska "wish"; Russian iskat' "to seek"; Lithuanian ieškau "to seek"; Latvian iēskât "to search for lice"; Armenian aic' "inspection, probe"; Latin aeruscare "to beg; go begging; get money traveling and practicing juggling"; Old High German eiscon "to desire"; Old English ascian "to ask"; English ask.
In contrast, the origin mentioned by traditional Persian lexicographers for ešq is the Arabic 'išq (عشق), from 'ašaq (عَشَق) "to stick, to cleave to". The latter is itself derived from 'ašaqa (عَشَقَه) the plant commonly called lablâb (لَبلاب) ("a kind of ivy"), because it twines upon trees, and cleaves to them (Zamaxšari, Tâj al-'arus).
It is interesting to note that ešq lacks a Hebrew counterpart; the Hebrew term for love is ahav, which is akin to Arabic habba (حَبَّ). Another Hebrew term used in the Old Testament is xašaq "to desire; to attach; delight, pleasure" (for example, Deu 10:15, 21:11; 1 Ki 9:19; Exo 27:17, 38:17; Gen 34:8). According to Prof. Scott B. Noegel, the Hebrew xašaq and Arabic 'ašaq are etymologically unrelated. The Hebrew x (heth) can equate either with an Arabic h (ḥā') or x (xā') and the Hebrew 'ayn can equate either with an Arabic 'ayn or qayn, but they do not mix. Also, typically the Hebrew š (shin) is reflected by an Arabic s (sin), and vise versa. As for the meanings, the similarity is a coincidence. Also, they are not ultimately of the same meaning. Hebrew x-š-q probably meant "to bind" or "press together", as does its Aramaic equivalent. Similarly, Prof. Werner Arnold underlines that Hebrew x in word initial positions is always an Arabic h (ḥā') and never 'ayn.
Note also that ešq ('išq) does not appear in the Koran, which instead uses the aforementioned verb habba (حَبَّ) and its derivatives, for example the noun hubb (حُبّ). Moreover, in Modern Arabic the relevant terms dominantly used are: habba and its derived forms hubb, habib, mahbub, etc.
The word ishq does not appear in the Quran, which instead uses derivatives of the verbal root habba (حَبَّ), such as the noun hubb (حُبّ). The word is traditionally derived from the verbal root ʿašaq "to stick, to cleave to" and connected to the noun ʿašaqah, which denotes a kind of ivy. In its most common classical interpretation, ishq refers to the irresistible desire to obtain possession of the beloved (ma‘shuq), expressing a deficiency that the lover (‘āshiq) must remedy in order to reach perfection (kamāl). Like the perfections of the soul and the body, love thus admits of hierarchical degrees, but its underlying reality is the aspiration to the beauty (al-husn) which God manifested in the world when he created Adam in his own image. Islamic conception of love acquired further dimensions from the Greek-influenced view that the notions of Beauty, Good, and Truth (al-haqq) "go back to one indissoluble Unity (wahda)".
Among classical Muslim authors, the notion of love was developed along three conceptual lines, conceived in an accending hierarchical order: natural love, intellectual love and divine love. The growth of affection (mawadda) into passionate love (ishq) received its most probing and realistic analysis in The Ring of the Dove by the Andalusian scholar Ibn Hazm. The term ishq is used extensively in Sufi poetry and literature to describe their selfless and 'burning love for Allah'. It is the core concept in the doctrine of Islamic mysticism as it is the key to the connection between man and God. Ishq itself is held to have been the basis of 'creation'.