Antonyms of adj accessorial

1 sense of accessorial

Sense 1
accessorial -- (nonessential but helpful; "accessorial services included sorting and packing")

INDIRECT (VIA inessential) -> essential -- (basic and fundamental; "the essential feature")

Similarity of adj accessorial

1 sense of accessorial

Sense 1
accessorial -- (nonessential but helpful; "accessorial services included sorting and packing")
       => inessential (vs. essential), unessential -- (not basic or fundamental)