Ritu ( sa, ऋतु) or Kaalanilai ( ta, காலநிலை) means "

season A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and ...

" in different ancient Indian calendars used in India, Bangladesh, Nepal and Sri Lanka. There are six ritus (also transliterated ritu) or seasons. The word is derived from the

Vedic Sanskrit Vedic Sanskrit was an ancient language of the Indo-Aryan subgroup of the Indo-European language family. It is attested in the Vedas and related literature compiled over the period of the mid- 2nd to mid-1st millennium BCE. It was orally prese ...

word Ṛtú, a fixed or appointed time, especially the proper time for sacrifice (

yajna Yajna ( sa, यज्ञ, yajña, translit-std=IAST, sacrifice, devotion, worship, offering) refers in Hinduism to any ritual done in front of a sacred fire, often with mantras.SG Nigal (1986), Axiological Approach to the Vedas, Northern Book ...

) or ritual in Vedic religion; this in turn comes from the word

Ṛta In the Vedic religion, ''Ṛta'' (; Sanskrit ' "order, rule; truth") is the principle of natural order which regulates and coordinates the operation of the universe and everything within it. In the hymns of the Vedas, ''Ṛta'' is described as ...

(ऋत), as used in

literally means the "order or course of things". This word is used in nearly all Indian languages.

North, West, Central Indian and Andhra Pradesh calendars

Nepal and India observes six ecological seasons.

East Indian calendars

East Indian calendars (Bengali, Assamese, Odia and Mithila) start their new year on Mesh Sankranti. The season names corresponds to the Sanskrit Vasanta, Grishma, Varsha, Sharada, Hemanta, Shishira order. The

Bengali Calendar The Bengali Calendar or Bangla Calendar ( bn, বঙ্গাব্দ , , Baṅgābda), colloquially ( bn, বাংলা সন, Baṅgla Śon), is a solar calendar used in the Bengal region of the Indian subcontinent. A revised version of t ...

is similar to the Sanskrit calendar above, but differs in start and end times which moves certain dates/days around (i.e., Vasant Panchami occurs here in Vasant ritu but in the calendar above, it occurs in Shishir as that is the Magha Shukla Panchami). The East Indian Calendar has the following seasons or ritus:

Bengali Calendar

Maithili Calender

Season in the Maithili Calendar

Odia Calendar

Seasons in the Odia calendar:

South Indian calendars

Malayalam Kannada Calendar

The

Malayalam calendar The Malayalam Calendar is a sidereal solar calendar used in Kerala. The origin of the calendar has been dated to 825 CE, the beginning of the Kollam Era. There are many theories regarding the origin of the era, but according to recent schola ...

or Kollam Era, a solar and sidereal

Hindu calendar The Hindu calendar, Panchanga () or Panjika is one of various lunisolar calendars that are traditionally used in the Indian subcontinent and Southeast Asia, with further regional variations for social and Hindu religious purposes. They adopt a ...

used in

Kerala Kerala ( ; ) is a state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile regions of Cochin, Malabar, South C ...

, and in Karnataka they follows a pattern of six seasons slightly different from North Indian Calendars.

Tamil calendar

The Tamil Calendar follows a similar pattern of six seasons as described for north Indian Hindu calendars which in fact need adjustment as taking new year from Grishma like that Bengali calendar....

In culture

The seasons are described in literature such as the

Sanskrit Sanskrit (; attributively , ; nominally , , ) is a classical language belonging to the Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had diffused there from the northwest in the la ...

poem '' Ṛtusaṃhāra'' written by the legendary Sanskrit poet

Kālidāsa Kālidāsa (''fl.'' 4th–5th century CE) was a Classical Sanskrit author who is often considered ancient India's greatest poet and playwright. His plays and poetry are primarily based on the Vedas, the Rāmāyaṇa, the Mahābhārata and ...

. Names of the ritu are commonly used for persons: typically, Vasant, Sharad, Hemant, Shishir and Varsh are "male" names; "female" names include Vasanti, Sharada, Hemanti, Grishma and Varsha. Similar naming conventions are also used in Tamil: For female Ilavenil. For male Kar(Vannan).