The term 'FIRST IN A SERIES' can be represented by five different crossword solutions: OPENER (6 letters), PILOT (5 letters), ONE (3 letters), ALPHA (5 letters), and PARTI (5 letters). OPENER is a word that refers to the beginning of something, such as a book or movie. PILOT is a term used to describe the FIRST episode of a television show. ONE is a number that signifies the FIRST in a sequence. ALPHA is the FIRST letter of the Greek alphabet, which is often used to refer to the FIRST of something. Finally, PARTI is a French word meaning 'FIRST'. All of these words can be used to describe the concept of being the FIRST in a series.