Antonyms of adj obstructive

1 sense of obstructive

Sense 1
clogging, hindering, impeding, obstructive -- (preventing movement; "the clogging crowds of revelers overflowing into the street")

INDIRECT (VIA preventive) -> permissive -- (not preventive)

Similarity of adj obstructive

1 sense of obstructive

Sense 1
clogging, hindering, impeding, obstructive -- (preventing movement; "the clogging crowds of revelers overflowing into the street")
       => preventive (vs. permissive), preventative -- (tending to prevent or hinder)