Kalyāṇa Varma, in his famous 10th century work ‘Sārāvalī’, devotes the entire 2nd chapter, albeit consisting of just 5 ślokas, to explaining the meaning of the word Horā.
Below is a word-by-word translation of the ślokas with commentary, and above are scans of this chapter in two editions:
modern edition with translation into English (translator and commentator - R. Santhanam),
critical edition in Sanskrit 1907 (editor - V. Subrahmanya Shastri).
I especially want to draw the reader’s attention to the last, fifth shloka, where Kalyāṇa Varma shares with us his thoughts about why we learn to read horoscopes in the first place, and how an astrologer can and should help a person who comes to him for a consultation.
द्वितीयोऽध्यायः । dvitīyo’dhyāyaḥ | Second Chapter
Translation: That line of letters which has been written on the forehead (likhitā yā ’sau lalāṭe ’kṣara-mālikā) by the Creator (vidhātrā) – an astrologer (‘knowing the destiny’) (daiva-jñas) would certainly read (tāṁ paṭhed vyaktaṁ) through spotless eye/sight of Horā (horā-nirmala-cakṣuṣā).
Commentary: Here the author for the first time quotes the word ‘Horā’, without yet explaining its meaning, and says that the astrologer will read the fate of the native, as if it were inscribed on their forehead by the Creator, with the help of the flawless vision of Horā, and we remember that Jyotiṣa Vedāṅga (‘part of the body’ of Vedas) is the eyes of the Vedas, along with other Vedāṅgas: Śikṣā (phonetics) – nose, Chandas (rhythm) – legs, Vyākaraṇa (grammar) – mouth, Nirukta (etymology) - ears, Kalpa (rituals and ceremonies) – hands.
Translation: The word ‘horā’ is derived (horā siddhyati) from the word ‘ahorātra’ (ahorātrāt) by removing the syllable from the beginning and from the end (ādy-antau-arṇa-lopād). And that [word] means (tat-pratibaddhaś) that (ayaṁ)zodiac with planets (graha-bha-gaṇaś) from which (yasmāt) the cause of obtaining fruits of karma (karma-phala-lābha-hetuṃ) for four [varṇas?] (caturāḥ) is considered (cintyate).
Commentary: Here Kalyāṇa Varma says that the word ‘Horā’ is derived by cutting off the first and last syllables of the word ahorātra, meaning ‘day and night’, that is the 24 hours – from dawn to the next dawn, and consisting of two words: ahas (day) and rātra (night). He also gives the first definition of the word ‘horā’ – the zodiac with planets. And he says that the planets and stars help to understand the reason for receiving the fruits of karma, thus recalling the theory of karma, the universal cause-and-effect law underlying Indian philosophy, for representatives of the four (it is not clear what the ‘four’ are – perhaps four varṇas (brāhmaṇa, kṣatriya, vaiśya, śudra) or for aśramas (brahmacharya, gṛhastha, vānaprastha, saṃnyāsa) – in the sense, for any person).
The difference is in the edition of V. Subramanya Shastri: horā siddhyati-ahorātrāt-> horā-śāstraṃ bhavati-ahorātrāt, the meaning is the same.
Translation: Others say (saṃvarṇayantyanye) – Horā is śāstra’s name (horā-iti śāstraṃ saṃjñā) for Lagna and also for half a rāśi (lagnasya tathā-ardha-rāśeś-ca).
Commentary: Kalyāṇa Varma gives the second and the third definitions of the word ‘Horā’ – the teaching about the lagna, and also the teaching about half the zodiac sign. The lagna here is understood not only as a sign or a point of the zodiac belt, which coincides with the position of the horizon at the time of birth, for a given place of birth; the word lagna also refers to a scheme of the 12 houses or signs of the zodiac, which is used as a horoscope.
The difference is in the edition of V. Subramanya Shastri: horāśāstraṃ s -> horeti śāstraṃ, the meaning is the same.
Translation: Birth chart (jātakam-iti) which is well known (prasiddhaṃ) in this world (yad-loke tad-iha) is called ‘horā’ (kīrtyate horā). Or rather (athavā) the method of investigation of destiny (daiva-vimarśana-paryāyaḥ) truly this word (khalu-ayaṃ śabdaḥ) [means].
Commentary: Kalyāṇa Varma gives the fourth and fifth definitions of the word ‘Horā’ – birth chart and the method by which the birth chart is studied to investigate the fate of the born. The Horā Śāstra is part of the Jyotiṣa Śāstra and includes four different directions - the birth chart (jātaka), the horoscope of the question (praśna), timing (muhūrta), omens and signs (nimitta).
Translation: There is no another (na-asti-aparaḥ) (1) helper in earning wealth (artha-arjane sahāyaḥ), (2) boat in a foaming sea of people’s calamity (puruṣāṇām-āpad-arṇave potaḥ), (3) advisor at the time of journey (yātrāṃ-samaye mantrī) except the birth chart (jātakam-apahāya).
Commentary: Kalyāṇa Varma talks about the purposes of reading the horoscope, and in what areas an astrologer can help a person who comes to him/her for consultation, namely – achieving material well-being; salvation from illness and misfortune; understanding the life/spiritual path, its goals, etc.
Translation: This is the second chapter (iti dvitīyo ’dhyāyaḥ) named ‘Thoughts on the meaning of the word Horā’ (horā-śabda-artha-cintā nāma)in Sārāvalī, composed by Kalyāṇa Varma (kalyāṇa-varma-viracitāyāṃ sārāvalyāṃ).