Please consider using "hearing impaired" as a more inclusive term, or ideally "deaf and hard of hearing". Their are plenty of people who can still hear some things but are not entirely deaf.
But that's actually why I use the term myself. I have found that euphemisms, including "hard of hearing" often don't successfully communicate what needs to be conveyed.
"Hard of hearing" just doesn't seem to sink in. Even "very hard of hearing" doesn't. Often the other person thinks it must be like struggling to hear the high notes in music or something. While I'm not deaf (and definitely not culturally Deaf), I generally can't understand spoken language without amplification. This often seems to surprise people, even when I've told them ahead that I'm hard of hearing.
"Nearly deaf" or "mostly deaf" would be accurate enough, but it feels odd and I don't like it. "Severe hearing impairment" communicates my experience, and also the accommodations I may need from others, quite effectively.