I'm not sure that 'piecemeal' has a precise opposite in a single word.
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http://allpoetry.com/poem/8439391-The_Canterbury_Tales__THE_CLERKES_TALE__a_-by-Geoffrey_Chaucer>
I blame hym thus, that he considereth noght
In tyme comynge what hym myghte bityde,
But in his lust present was al his thoght,
As for to hauke and hunte on every syde.
Wel ny alle othere cures leet he slyde;
And eek he nolde,-and that was worst of alle-
Wedde no wyf, for noght that may bifalle.
Oonly that point his peple bar so soore,
That flokmeele on a day they to hym wente,
And oon of hem, that wisest was of loore,
Or elles that the lord best wolde assente,
That he sholde telle hym what his peple mente,
Or elles koude he shewe wel swich mateere,
He to the markys seyde as ye shul heere:
Chaucer seems to use 'flockmeal' in the sense defined here:
flock-meal, by companies or troops (of persons), rarely by groups or
heaps (of things)
[...]
piecemeal, one part or piece at a time, in separate pieces, by
degrees, little by little
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http://laudatortemporisacti.blogspot.co.uk/2008/09/flockmeal-etc.html>
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-- Whiskers
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