(1) Circle.
(2) Wheel.
(3) Divine Disc - Sudarshan Chakra. One of the four things Vishnu holds in His hands called Sudarshan. The other three are Paanchjanya Shankh (conch shell), Kaumodakee Gadaa (mace) and Padm (lotus flower).

(4) Its another meaning is in context of Yog science. According to it, our body has seven Chakra or seven centers of consciousness located along the spinal column - three in the upper hemisphere of the body and three in the lower hemisphere of the body and one in the center.

(i) Moolaadhaar Chakra - This is the first Chakra located at the base of the spine. This is the root Chakra - the center for the earth element. It is the center that is the base of worship for the Kaulaa school of Tantra.

(ii) Swaadhishthaan Chakra

(iii) Manipur Chakra - The Chakra which is filled jewels; naval center; the center of the fire element; the solar plexus.

(iv) Anahat Chakra - This is the fourth Chakra in the row which is located in the center, the heart center, and has its location between the upper and lower hemispheres of the body. It is the center of the air element. Practices involving Anahat Chakra are always recommended to control Bhava, which means to balance emotional life as well as the problem of inertia or sleep. If a beginner is not yet competent to meditate on this Chakra, he experiences sleep-like inertia or dozes. Students of Mishra school of Tantra perform their worship at this Chakra.

(v) Vishuddh Chakra - Throat center (above heart); center of the space element.

(vi) Aagyaa Chakra - 

(vii) Sahasraar Chakra - This Chakra is situated at the top and that is why is called Crown Chakra also. The seat, sphere, or abode of Brahm. Also called Brahm Puree.

Bhaagvat Puraan, 2/1 describes only 5 Chakra's names like this - Manipoorak, Anaahat, Vishuddh, Aagyaa, Sahasraar.

Shriram Sharmaa, the founder of "Shantikunj, Haridwaa" mentions six Chakra as "Shat Chakra" in his book "Super Science of Gayatri" but does not count the Sahasraar Chakra along with all other Chakra - (1) Moolaadhaar Chakra lying in the genital region; (2) Swadhisthaan Chakra lying in the portion between the navel and the pubic region; (3) Manipur Chakra lying in the umbilicus region; (4) Anahat Chakra lying near the heart; (5) Vishudaakhya Chakra near the neck; (6) Aagyaa Chakra lying in the middle of both the eye-brows; and above all lies (7) Sahasraar Chakra in the brain.