‘sama’ means equality – no high, no low. There are other meanings also. What is full or complete is also said to be ‘sama’. ‘samAdhAna’ means to unify the mind and establish it completely in one place.
It should not be allowed to move this side or that side. We all know the mind thinks of several things at the same time. To converge it into one place and firmly establish it there is ‘sama AdhAnaM’ or ‘samAdhAnaM’. The one who has so established the mind by fixing it in one place is a ‘samAhita’.
By doing this the perturbations of the mind are all calmed and it becomes focussed completely at one place. By such a ‘samAdhAna’ the peace of a calm restful mind is obtained. What is that one thing into which the mind is to be focussed without running into all directions?
*shuddhe brahmaNi* : ‘In the pure unmixed Brahman’. To establish the mind always and in all manner, completely in Brahman is ‘samAdhAnaM’.
*samyak AsthApanaM buddheH shuddhe brahmaNi sarvadA / tat-samAdhAnam-ityuktaM …. //*
This is how the Acharya defines it in Vivekachudamani shloka 26 (27). ‘samyak’ means ‘correctly’ or ‘completely’. Here both meanings have to be taken in. ‘AsthApanaM’ means ‘ the establishing of’.
‘The intellect has to be always (*sarvadA) established completely in Brahman in the right manner (*samyak*); this establishing is said to be (*ityuktaM*) samAdhAnaM’.