BOISTOUS

DEFINITIONS CONTINUED
NOUN
4. coarse in texture, gross, rough; thick, stiff (obsolete)
5. rough, loud, or violent in sound; noisy, boisterous (obsolete)
6. of the wind, sea, weather: rough and violent; boisterous (obsolete)
7. stubborn, churlish (obsolete)
8. halting, lame (obsolete)
9. fat, corpulent (dialect)

also bioustious, boiseose, boisteous, boistez, boistoys, booistous, bostuous, bostyous, boysteis, boysteous, boystious, boystoyse, boystous, boystows, boystuous, boystyous, buistous, busteous, buystous, buystuous

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from E-NED:
of uncertain etymology;
Certainly not connected with bost, boast (as has been suggested on the ground of the
16th century Scottish spelling boist for bōst). 
The phonology and form suggest French origin, and in form the Middle English word 
exactly answers to Old French boisteus, AF. boistous, modern French boiteux lame;
but no connexion of sense appears to be traceable, at least if the etymology proposed 
by Diez for the French word from boiste ‘box’, ‘knee-joint’ holds good. 
The essential meaning in English from the first appears to have been ‘coarse, rough’, 
but senses 1–4 are all nearly equally early. 
The later variants boisteous, boystuous, led to the modern boisterous.
(The modern Cornwall dialect has in West Cornwall boist corpulence, 
boustis, bustious stout, overfat, burdensome to oneself;
in East Cornwall boostis fat, well-conditioned: 
cf. sense 3. This occurrence of a sense so long obsolete in literary English, and 
especially of an apparent radical noun boist, not known at all in literature, 
is very curious: but there are no similar words known in Celtic Cornish. 
The Welsh bwyst ‘wildness’ appears to be a figment of Owen Pugh, 
but bwystus ‘wild, ferocious’ occurs in the 14th century, and may be a derivative 
of an obsolete *bwyst:—Latin bēstia; or it may be merely the Middle English buystous.)

c 1300 - King Alisaunder;
see below From: Metrical Romances of the 13th, 14th, and 15th Centuries
By Henry Weber
Volume I, 1810
Kyng Alisaunder
P. 234
(for definition 1)

From: Fasti Eboracenses: 
Lives of the Archbishops of York
By William Henry Dixon
Edited by the Rev. James Raine
Volume I. 1863
Archbishop Thoresby (1361)
P. 461