Deaf vs. Hearing Impaired
Outside of the deaf community deaf usually means a total hearing loss and someone with a partial hearing loss is more likely to be referred to as hearing impaired. These terms are used in the pathological sense, to indicate an illness or disability.
Political correctness has led to a preference, by hearing people, for referring to a person as hearing impaired rather than deaf. In this sense it is a euphemism for deaf. In fact, Deaf people who consider themselves part of the cultural and linguistic minority, the "Deaf World," take great affront at the use of the term "hearing impaired." They consider it a politically incorrect term.
In contrast, the Deaf cultural world view uses the terms Deaf, hard-of-hearing and hearing in an "us" or "them" sense. In this view "Deaf" (us) means to experience the world and embrace the values that Deaf people embrace (notice the capital "D"), while "hearing" (them) means to experience the world and embrace the values that hearing people embrace. This creates a Deaf cultural view in which hard-of-hearing represents a view of the world that embraces values from both the Deaf and hearing world. Indeed, within Deaf culture the terms "hearing" and "hard-of-hearing" are sometimes used to denigrate, provoke or insult both Deaf and hearing people. Deaf students from one school have been known to playfully refer to deaf students from another school as "hearing" during athletic competition. Historically speaking, Deaf culture has never embraced the term "hearing impaired" in this "us" versus "them" view because it is thought to be a generalization on pathology that tells nothing about an individual's values. Further, the deaf view of this terminology parallels that of a language minority rather than being a description of pathology or disability. The term "deaf" has been the traditional identification of culturally Deaf people for over two and a half centuries, or before the serious examination of hearing loss by medical practitioners and speech teachers, who introduced pathological terminology such as "semi-deaf", "semi-mute" and the modern "hearing impaired" to the language, even began. "Deaf" remains the preferred term of group identification among culturally deaf people today. Members of the Deaf community often interact through organization such as the National Association of the Deaf and through culturally Deaf web portals such as DeafSpot.net. These organizations and web sites are cultural artifacts, not self-help or medical resources.
Not all people who view themselves as deaf are nasty to hearing people. They simply don't like being referred to as impaired (i.e., broken). Some deaf people refer to hearing people as Deaf impaired as a joke, to make fun of the "hearing impaired" label.
Total deafness is quite rare. In fact, most people who are in the "Deaf World" can hear a little, but since hearing loss is frequency-based rather than amplitude-based, a deaf person's hearing is not usable. (They can usually only hear bass sounds and/or really high-pitched sounds, if anything.) Therefore, they, and deaf-friendly hearing people, believe the narrow "total hearing loss" definition of deaf is inaccurate because they have the same needs as someone who is totally deaf.
Other Meanings:
Deaf is also used as a colloquialism to refer to a recalcitrant individual or someone unwilling to listen, obey or acknowledge an authority or partner. The third line of Shakespeare's Sonnet 29 provides an example:
"When in disgrace with fortune and men's eyes
I all alone beweep my outcast state,
And trouble deaf heaven with my bootless cries,"