Definition of high-vis in US English:

high-vis

(also hi-vis)

adjective

informal
  • ‘railway workers in high-vis jackets’
    short for high-visibility
    • ‘The mystery thief has been caught on camera wearing an orange high-vis vest - the same worn by genuine railway staff - to pass under the noses of the public at four busy stations.’
    • ‘They wear all the gear, includng ridiclously tight cycling pants, day-glo high-vis vests, goggles, face masks, even cycling shoes that clip into the pedals.’
    • ‘After a short safety talk and kitted out in gloves and high-vis jackets, we picked up a shovel and pitch fork and got digging.’
    • ‘I usually wear a hi-vis jacket and a cycle helmet too, not because they're required but just to add to visibility.’
    • ‘It was a very high-vis mission, and there was many a tense moment.’
    • ‘High-vis boilersuits in particular are used by those working on roads, near railways or at night, where visibility is a concern.’
    • ‘When road-running, make sure you are visible - even in daylight, hi-vis clothing makes you far more easily seen by motorists.’

Pronunciation

high-vis

/hīˈviz/