The term 'OUTER COVERING OF A FLOWER' can be summarized as the CALYX, which is a five-letter word. The CALYX is the outermost layer of a flower, consisting of sepals that form a protective covering for the petals and reproductive organs. It is typically green in color and can be either fused or separate. The CALYX is an important part of the flower's anatomy, as it helps to protect the flower from environmental damage and pests.