sign language 
noun [mass noun]
A system of communication using visual gestures and signs, as used by deaf people.If the linguistic space is sign language, then the deaf infant will acquire language in that modality....
- The videophone is already being used to let patients talk remotely to doctors, and by deaf people to communicate in sign language.
- She was phenomenal - she trained for about two months with a deaf lady and learnt sign language.
- digger's hat
- digger wasp
- diggings
- digging stick
- dight
- digibox
- digicam
- dig in one's heels (or toes or feet)
- digipak
- digit
- digital
- digital art
- digital audio
- digital audio broadcasting
- digital audiotape
- digital calculator
- digital camera
- digital cash
- digital compact cassette
- digital compression
- digital computer
- digital delay
- digital detox
- digital divide
- digital download