-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.
(physics, mechanics) The turning effect of a force applied to a rotational system at a distance from the axis of rotation. Also called moment of force. (historical) A definite period of time, specifically one-tenth of a point, or one-fortieth or one-fiftieth of an hour. (informal) A petit mal episode; such a spell.