It is the duration of time in which the difference of the longitudes of the Sun and the Moon is increased by 6 degrees.
Of these 11 names, four are fixed or immovables (or sthira-s) in the sense that they are associated with four unique karaṇa-s in a lunar month.
These names are Bava, Bālava, Kaulava, Taitila, Gara, Vaṇij and Vṛṣṭi.
[2] In the Malayalam astronomical literature, the eleven karaṇas are assigned names which are words for various animals.
So the origination of the oncept of karaṇa-s can be traced to as early as the period of Vedāṅga Jyotiṣa, that is, around 500 BCE.