thumb|Cover of a modern copy of Amara kosha
The Amarakosha (Devanagari: अमरकोशः , IAST: Amarakośaḥ , ISO: Amarakōśaḥ ) is the popular name for Namalinganushasanam (Devanagari: नामलिङ्गानुशासनम् ,  IAST: Nāmaliṅgānuśāsanam , ISO: Nāmaliṅgānuśāsanam ) a thesaurus in Sanskrit written by the ancient Indian scholar Amarasimha.
It may be one of the oldest extant koshas.
The author himself mentions 18 prior works, but they have all been lost.
There have been more than 40 commentaries on the Amarakosha.
Etymology
The word "Amarakosha" derives from the Sanskrit words amara ("immortal") and kosha ("treasure, casket, pail, collection, dictionary").
The actual name of the book "Namalinganushasanam" means "instruction concerning nouns and gender".
Author
Narasimha is said to have been one of the Navaratnas ("nine gems") at the court of Vikramaditya, the legendary king inspired by Chandragupta II, a Gupta king who reigned around AD 400.
Some sources indicate that he belonged to the period of Vikramaditya of the 7th century.Amarakosha compiled by B.L.Rice, edited by N.Balasubramanya, 1970, page X
Mirashi examines the question of the date of composition of Amarakosha.
He finds the first reliable mention in Amoghavritti of Shakatayana composed during the reign of Amoghavarsha (814-867 CE).
Literary and Historical Studies in Indology, Vasudev Vishnu Mirashi, Motilal Banarsidass Publ., 1975, p. 50-51 Textual organisation
The Amarakosha consists of verses that can be easily memorized.
It is divided into three s or chapters.
The first,  ("heaven and others") has words about gods and heavens.
The second,  ("earth and others") deals with words about earth, towns, animals, and humans.
The third,  ("common") has words related to grammar and other miscellaneous words.
Svargadhikhaanda, the first Khanda of the Amarakosha begins with the verse 'Svaravyam swarganakathridivatrishalaya..'
describing various names of Heaven viz.
Sva, Avya, swarga, Naka, Tridiva, Tridasalaya etc.
The second verse 'Amara, Mirjana, deva,’ describes various words that are used for gods and demigods.
The fifth and sixth verses give various names of Buddha and Shakyamuni (i.e. Gautam Buddha).
The following verses give the different names of Brahma, Vishnu, Vasudeva, Balarama, Kamadeva, Lakshmi, Krishna, Shiva, Indra, the, etc.
All these names are treated with great reverence.
While Amara Simha is regarded to have been a Buddhist,Encyclopaedia of Indian Literature: Devraj to Jyoti, Volume 2, Editor	Amaresh Datta, Sahitya Akademi, 1988 p. 1036A History of Indian Literature, Moriz Winternitz, Motilal Banarsidass, 1985, p. 494 Amarakosha reflects the period before the rise of sectarianism.
Commentaries on Amarakosha have been written by Brahmanical, Jain and well as Buddhist scholars.Anundoram Barooah  Makers of Indian literature, Biswanarayan Shastri, Sahitya Akademi, 1984p. 79
The second Kanda, Bhuvargadhikanda, of the Amarakosha is divided into ten Vargas or parts.
The ten Vargas are Bhuvarga (Earth), Puravarga (Towns or Cities), Shailavarga (Mountains), Vanoshadivarga (Forests and medicines), Simhadivarga (Lions and other animals), Manushyavarga (Mankind), Bramhavarga (Brahmin), Kshatriyavarga (Kshatriyas), Vysyavarga (Vysyas) and Sudravarga (Sudras).
The Third Kanda, Samanyadhikanda contains Adjectives, Verbs, words related to prayer and business, etc.
The first verse Kshemankaroristatathi Shivathathi Shivamkara gives the Nanarthas of the word Shubakara or propitious as Kshemankara, Aristathathi, Shivathathi, and Shivamkara.
Commentaries
Amarakoshodghātana by  Kṣīrasvāmin (11th century CE, the earliest commentary)
Tīkāsarvasvam by Vandhyaghatīya Sarvānanda (12th century)
Rāmāsramī (Vyākhyāsudha) by Bhānuji Dīkshita
Padachandrikā by Rāyamukuta
Kāshikavivaranapanjikha by Jinendra Bhudhi
Pārameśwari by Parameswaran Mōsad in Malayalam
A Telugu commentary by Linga Bhatta (12th century)
Translations
"Gunaratha" of Ujjain translated it into Chinese in the 7th century.
The Pali thesaurus Abhidhānappadīpikā, composed in the twelfth century by the grammarian Moggallāna Thera, is based on the Amarakosha.
References
Bibliography
Krsnaji Govinda Oka, Poona City, Law Printing Press, 1913
Amarakosha at sanskritdocuments.org
Amarakosha files by Avinash Sathaye
The Nâmalingânusâsana (Amarakosha) of Amarasimha; with the commentary (Amarakoshodghâtana) of Kshîrasvâmin (1913) at the Internet Archive.
A web interface to access the knowledge structure in Amarakosha at Department of Sanskrit Studies, University of Hyderabad.
