Etymology and names
The word "Ayodhya" is a regularly formed derivation of the Sanskrit verb yudh, "to fight, to wage war". Yodhya is the future passive participle, meaning "to be fought"; the initial a is the negative prefix; the whole, therefore, means "not to be fought" or, more idiomatically in English, "invincible". This meaning is attested by the Atharvaveda, which uses it to refer to the unconquerable city of gods. The 9th century Jain poem Adi Purana also states that Ayodhya "does not exist by name alone but by the merit" of being unconquerable by enemies. Satyopakhyana interprets the word slightly differently, stating that it means "that which cannot be conquered by sins" (instead of enemies).
"Saketa" is the older name for the city, attested in Buddhist, Jain, Sanskrit, Greek and Chinese sources. According to Vaman Shivram Apte, the word "Saketa" is derived from the Sanskrit words Saha (with) and Aketen (houses or buildings). The Adi Purana states that Ayodhya is called Saketa "because of its magnificent buildings which had significant banners as their arms". According to Hans T. Bakker, the word may be derived from the roots sa and ketu ("with banner"); the variant name saketu is attested in the Vishnu Purana.
Ayodhya was stated to be the capital of the ancient Kosala kingdom in the Ramayana. Hence it was also referred to as "Kosala". The Adi Purana states that Ayodhya is famous as su-kośala "because of its prosperity and good skill".
The cities of Ayutthaya (Thailand), and Yogyakarta (Indonesia), are named after Ayodhya.