Parjanya, according to the 1965 Sanskrit–English dictionary by Shri Vaman Shivram Apte gives the following meanings:

• Rain-cloud, thunder cloud, a cloud in general
• Rain (as referred in the Shloka
  Shloka
  A ' is a category of verse line developed from the Vedic Anuṣṭubh. It is the basis for Indian Epic verse, and may be considered the Indian verse form par excellence, occurring, as it does, far more frequently than any other meter in classical Sanskrit poetry. The Mahabharata and Ramayana, for...
  
   from Bhagavad Gita
  Bhagavad Gita
  The ' , also more simply known as Gita, is a 700-verse Hindu scripture that is part of the ancient Sanskrit epic, the Mahabharata, but is frequently treated as a freestanding text, and in particular, as an Upanishad in its own right, one of the several books that constitute general Vedic tradition...
  
   Chapter 3 Verse 14)
• The god (deva) of rain i.e. Indra
  Indra
  ' or is the King of the demi-gods or Devas and Lord of Heaven or Svargaloka in Hindu mythology. He is also the God of War, Storms, and Rainfall.Indra is one of the chief deities in the Rigveda...
  
  

Two hymns of the Rigveda, 5.63 and 7.101, are dedicated to Parjanya. In Vedic Sanskrit

Vedic Sanskrit

Vedic Sanskrit is an old Indo-Aryan language. It is an archaic form of Sanskrit, an early descendant of Proto-Indo-Iranian. It is closely related to Avestan, the oldest preserved Iranian language...

 Parjanya means "rain

Rain

Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...

" or "raincloud". Prayers dedicated to Parjanya, to invoke the blessings of rains are mentioned in the Atharva Veda.

Parjanya was also one of the Saptarishi (Seven Great Sages Rishi

Rishi

Rishi denotes the composers of Vedic hymns. However, according to post-Vedic tradition, the rishi is a "seer" to whom the Vedas were "originally revealed" through states of higher consciousness. The rishis were prominent when Vedic Hinduism took shape, as far back as some three thousand years...

) in the fifth Manvantara

Manvantara

Manvantara or Manuvantara , or age of a Manu , the Hindu progenitor of mankind, is an astronomical period of time measurement. Manvantara is a Sanskrit sandhi, a combination of words manu and antara, manu-antara or manvantara, literally meaning the duration of a Manu, or his life span .Each...

. He is one of the 12 Adityas

Ādityas

In Hinduism, Āditya , meaning "of or related to Aditi", refers to the offsprings of Aditi. Adityas are solar class deities. In later Hinduism, Aditya is used in the singular to mean the sun.-Vedas:...

 and according to the Vishnu Purana

Vishnu Purana

The Vishnu Purana is a religious Hindu text and one of the eighteen Mahapuranas. It is considered one of the most important Puranas and has been given the name Puranaratna...

, the guardian of the month of Kartik

Kartik

Kartik may refer to:* Kartika , a month in the Indian national calendar and Bengali calendar* Kartik * Karttikeya, the brother of Ganesha in the Hindu mythology...

, a Gandharva

Gandharva

Gandharva is a name used for distinct mythological beings in Hinduism and Buddhism; it is also a term for skilled singers in Indian classical music.-In Hinduism:...

 and a Rishi

Rishi

Rishi denotes the composers of Vedic hymns. However, according to post-Vedic tradition, the rishi is a "seer" to whom the Vedas were "originally revealed" through states of higher consciousness. The rishis were prominent when Vedic Hinduism took shape, as far back as some three thousand years...

 in the Harivamsa

Harivamsa

The Harivamsha is an important work of Sanskrit literature, containing 16,374 verses, mostly in metre. The text is also known as . This text is believed as a khila to the Mahabharata and is traditionally ascribed to Krishna Dvaipayana Veda Vyasa...

. The name may be cognate with Lithuanian

Lithuanian language

Lithuanian is the official state language of Lithuania and is recognized as one of the official languages of the European Union. There are about 2.96 million native Lithuanian speakers in Lithuania and about 170,000 abroad. Lithuanian is a Baltic language, closely related to Latvian, although they...

 Perkūnas

Perkunas

Perkūnas was the common Baltic god of thunder, one of the most important deities in the Baltic pantheon. In both Lithuanian and Latvian mythology, he is documented as the god of thunder, rain, mountains, oak trees and the sky.-Etymology:...

"god of thunder", Finnish

Finnish language

Finnish is the language spoken by the majority of the population in Finland Primarily for use by restaurant menus and by ethnic Finns outside Finland. It is one of the two official languages of Finland and an official minority language in Sweden. In Sweden, both standard Finnish and Meänkieli, a...

 Perkele

Perkele

Perkele is the god associated with thunder in Finnish mythology, like Thor of Norse mythology. In modern Finnish perkele is a common swearword.-Origins:The name is of Indo-European origin...

"god of thunder", Gothic

Gothic language

Gothic is an extinct Germanic language that was spoken by the Goths. It is known primarily from the Codex Argenteus, a 6th-century copy of a 4th-century Bible translation, and is the only East Germanic language with a sizable Text corpus...

 fairguni "mountain", Mordvin language Pur’ginepaz, see Perkwunos.

Reference from Bhagavad Gita Chapter 3 Verse 14

annād bhavanti bhūtāni

parjanyād anna sambhavaḥ

yajħād bhavati parjanyo

yajħaḥ karma samudbhavaḥ

Living beings are created and find their source in food, food is created by rainfall,. Parjanya gives us the material blessings of rainfall and thus abundance in the material world by the creation of food and other crops.

Rig Veda hymns to Parjanya

RV 5.63 in the translation of Griffith

Ralph T.H. Griffith

Ralph Thomas Hotchkin Griffith , scholar of indology, Son of B.A. of Queen's College was elected to the vacant Sanskrit Scholarship on Nov 24, 1849. He translated the Vedic scriptures into English. He also produced translations of other Sanskrit literature, including a verse version of the...

:

1a

1c

Sing with these songs thy welcome to the Mighty, with adoration praise and call Parjanya.

The Bull, loud roaring, swift to send his lays in the plants the seed for germination.

2a

2c

He smites the trees apart, he slays the demons: all life fears him who wields the mighty weapon.

From him exceeding strong flees e'en the guiltless, when thundering Parjanya smites the wicked.

3a

3c

Like a car-driver whipping on his horses, he makes the messengers of rain spring forward.

Far off resounds the roaring of the lion, what time Parjanya fills the sky with rain-cloud.

4a

4c

Forth burst the winds, down come the lightning-flashes: the plants shoot up, the realm of light is streaming.

Food springs abundant for all living creatures, what time Parjanya quickens earth with moisture.

5a

5c

Thou at whose bidding earth bows low before thee, at whose command hoofed cattle fly in terror,

At whose behest the plants assume all colours, even thou Parjanya, yield us great protection.

6a

6c

Send down for us the rain of heaven, ye Maruts, and let the Stallion's flood descend in torrents.

Come hither with this thunder while thou pourest the waters down, our heavenly Lord and Father.

7a

7c

Thunder and roar: the germ of life deposit. Fly round us on thy chariot waterladen.

Thine opened water-skin draw with thee downward, and let the hollows and the heights be level.

8a

8c

Lift up the mighty vessel, pour down water, and let the liberated streams rush forward.

Saturate both the earth and heaven with fatness, and for the cows let there be drink abundant.

9a

9c

When thou, with thunder and with roar, Parjanya, smitest sinners down,

This universe exults thereat, yea, all that is upon the earth.

10a

10c

Thou hast poured down the rain-flood now withhold it. Thou hast made desert places fit for travel.

Thou hast made herbs to grow for our enjoyment: yea, thou hast won thee praise from living creatures.