dharmacakra[dhammacakka] the wheel of the Doctrine. Dharma means the truth, wisdom or knowledge; cakra means a wheel or establishment. Dharmacakra, the compound word means the Doctrine or the Law established by Gautama Buddha. The doctrine alludes to the Four Noble Truths. The perfect one, the fully enlightened one, set rolling the unsurpassed wheel of the Law in the Deer Park at Isipatana also known as Sarnath near Vārāṇasī.

Buddhānusmṛti - A Glossary of Buddhist Terms

Aṭṭhasālinī. Nidāna. 90, 119. Dīgha Nikāya. Mahāparinibbāna. Lalita-Vistara. XXVI. 337-360. Mahāyāna-Sūtrālaṅkāra. XIX. 167. Saddharmapuṇḍarīkasūtram. II. 80. Saṃyutta Nikāya. Dhammacakkappavattana. Vinaya. Mahāvagga I.1.6.

○cakra n. the wheel or range of the law MBh. Buddh. Jain.
• a partic. mythical weapon Hariv. R.
• m. 'having or turning the wheel of the law', a Buddha L.
• -bhṛt m. holding the wheel of the law', a Buddha or Jaina L.

Sanskrit-English Dictionary, by M. Monier William