preventive
pre-ven-tive
adjective
Intended to stop something undesirable, like illness or crime, from happening.
"They took preventive measures against the virus."
noun
A medicine or action taken to stop disease or difficulty from occurring.
"The vaccine acts as a preventive against the flu."
Thesaurus
Synonyms: pre-emptive, obstructive, preemptive, hindering, frustrative, clogging, prohibitory, impeding, preclusive, deterrent, blockading, preventative
Antonyms: permissive