-blast. A suffix meaning an immature precursor cell of the type indicated by the preceding word. [G. blastos, germ]. immature precursor cell type; the cell type is denoted by the preceding syllables, e.g. osteoblast.
(plural defining moments) A moment in time that defines something, such as a person's success or failure, achievement or demise, talent, etc. A point at which the essential nature or character of a person, group, etc., is revealed or identified.
How Long Is a Moment? In modern English, the term moment refers to an unspecific short amount of time. The term is thought to date to the 14th century and was used to refer to a period of 90 seconds. An hour in medieval times therefore consisted of 40 moments. The Hebrew calendar has a shorter definition of a moment, referred to as rega, which is roughly equivalent to 5/144 of a second.