Viveka has always had the meaning of "seclusion". But it is much more than that.
The gist of Buddhism is discernment (pañña) - pañña in its all encompassing meaning - and viveka is just about getting to that.
Discrimination between the external (the khandhas of nāmarūpa of which we are fed,) and the internal, in satta.
So "seclusion," yes! - but also "detachment". As in "discrimination" and "separation from" one of the two components involved; before you go to "seclusion".
In other words:
Rapture and pleasure of the body, born of discrimination between the external & the internal - separation from the external - and then seclusion in the internal.
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Lexical references:
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PALI
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Viveka [fr．vi+vic]
- detachment, loneliness, separation, seclusion; “singleness” (of heart), discrimination （of thought） [PTS]
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SANSKRIT
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विवेक viveka [act. vivic]
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True knowledge , discretion , right judgement , the faculty of distinguishing and classifying things according to their real properties ChUp.
विविच् vivic [ vi-√ vic ]
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- divide asunder , separate from ŚBr.
- to distinguish , discern , discriminate KaṭhUp. (somewhat contemporary)
- to go asunder , separate AV.
√ विच् vic [linked to vij]
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- to sift , separate (esp. grain from chaff by winnowing) RV. AV.
- to discriminate , discern , judge RV. AV.
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