The term 'BIRD-TO-BE' can BE broken down into two parts: 'BIRD' and 'TO-BE'. The first part, 'BIRD', can BE further broken down into the crossword solution 'EGG', which is a three letter word. An EGG is the first stage of a BIRD's life cycle, and it is the beginning of the process of a BIRD becoming a fully grown adult. The second part, 'TO-BE', implies that the BIRD is in the process of becoming something, and this could refer TO the BIRD's growth from an EGG TO an adult. Therefore, the term 'BIRD-TO-BE' can BE interpreted as the process of a BIRD growing from an EGG TO an adult.