em·dash or em dash 
(ĕmdăsh′)
(ĕmdăsh′)n.
A symbol ( — ) used in writing and printing to indicate a break in thought or sentence structure, to introduce a phrase added for emphasis, definition, or explanation, or to separate two clauses.
[From its being the width of an m in printing.]
- paraphyly
- paraphysis
- paraplegia
- paraplegic
- parapodium
- parapraxis
- paraprofessional
- parapsychic
- parapsychological
- parapsychologist
- parapsychology
- paraquat
- parasail
- parasailer
- parasang
- paraselene
- paraselenic
- parasexual
- parasexuality
- parasexually
- parasite
- parasitic
- parasitical
- parasitically
- parasiticidal