What is referred to by 'alphabetic sign language'?

Based on the clue 'alpha centauri is a star this 3 letters shorter is...', what is the answer? Based on the clue 'alpha delta pi sandra palmer is known for putterin...', what is the answer? What is associated with: alpha phi alpha john h johnson founded this magazine in 1951 6 years after ebony? Based on the clue 'alpha waves occur when youre relaxed with eyes clo...', what is the answer? Based on the clue 'alphabetically a select list of endangered species...', what is the answer? Based on the clue 'alphabetically baseball hall of famers run from hi...', what is the answer? Based on the clue 'alphabetically by first name hes listed last', what is the answer? Based on the clue 'alphabetically by last name hes listed last', what is the answer?