The term 'CELTICS GREAT' is a reference to the legendary basketball player Larry BIRD, who played for the Boston Celtics from 1979 to 1992. His four-letter nickname, 'BIRD, ' is the answer to the first crossword clue, and his full name, 'Larry BIRD, ' is the answer to the second clue. During his time with the Celtics, Larry BIRD was an 11-time All-Star, 3-time MVP, and 2-time NBA champion. He was inducted into the Basketball Hall of Fame in 1998 and is widely considered one of the greatest players in NBA history.