According to Pitarau.com, the Adityas (plural) are a group of sun gods (the sons of Aditi and Kashyapa). The website also gives this info: "[in Tamil Aditya] 1. The son of Aditi (i.e. the Sun). 2. The 40th and 563rd names of Lord Vishnu as listed in the Vishnu Sahasranama. In his commentary Sri Sankara states,'1) Aditya is the golden being residing in the orb of the sun. 2) It is also Vishnu among the twelve Adityas, as is said in the Bhagavad Gita X:21. 3) He is also the consort of the undivided Mother Earth, as is said in the Vedas. 4) It again refers to His dwarf incarnation from Aditi and Kashyapa. 5) Or it refers to an analogy of the one sun being reflected as many in several water-pots with the one Self being reflected as many in various bodies.' Also see the Bhagavad Gita V:16; VIII:9; XI: 12; XIII:33; XV:12." Source: http://www.pitarau.com/nd/All/AdityaOn Wikipedia, it says that "In later Hinduism, Aditya is used in the singular to mean the sun." And again, "In present day usage in Sanskrit, the term Aditya has been made singular in contrast to Vedic 'Adityas', and is being used synonymously with 'Surya', the Sun." http://en.wikipedia.org/wiki/AdityaIf you look elsewhere on Indian baby name sites, Aditya is usually given to mean "the sun". So that does seem to be how it is used today. 'Adi' is used as the short form/nickname.
The website also gives this info: "[in Tamil Aditya] 1. The son of Aditi (i.e. the Sun). 2. The 40th and 563rd names of Lord Vishnu as listed in the Vishnu Sahasranama. In his commentary Sri Sankara states,'1) Aditya is the golden being residing in the orb of the sun. 2) It is also Vishnu among the twelve Adityas, as is said in the Bhagavad Gita X:21. 3) He is also the consort of the undivided Mother Earth, as is said in the Vedas. 4) It again refers to His dwarf incarnation from Aditi and Kashyapa. 5) Or it refers to an analogy of the one sun being reflected as many in several water-pots with the one Self being reflected as many in various bodies.' Also see the Bhagavad Gita V:16; VIII:9; XI: 12; XIII:33; XV:12."
Source: http://www.pitarau.com/nd/All/Aditya
On Wikipedia, it says that "In later Hinduism, Aditya is used in the singular to mean the sun."
And again, "In present day usage in Sanskrit, the term Aditya has been made singular in contrast to Vedic 'Adityas', and is being used synonymously with 'Surya', the Sun."
http://en.wikipedia.org/wiki/Aditya
If you look elsewhere on Indian baby name sites, Aditya is usually given to mean "the sun". So that does seem to be how it is used today. 'Adi' is used as the short form/nickname.