noun
: any of four flammable liquid alcohols C 4 H 9 OH derived from the butanes and used chiefly in organic synthesis and as solvents often in the form of their esters:
a. : the normal alcohol CH 3 CH 2 CH 2 CH 2 OH made by bacterial fermentation of molasses or grain or synthetically (as by dehydration and reduction of aldol); 1-butanol — called also n-butyl alcohol
b. : the secondary alcohol CH 3 CH 2 CH(OH)CH 3 known in three optically different forms and made by hydration of 1-butene; 2-butanol — called also sec-butyl alcohol
c. : the tertiary alcohol (CH 3 ) 3 COH made by hydration of isobutylene; 2-methyl-2-propanol — called also tert-butyl alcohol, trimethylcarbinol
d. : isobutyl alcohol