blast

https://doi.org/10.1351/goldbook.12952
Immature stage in cell development, before the appearance of the definitive characteristics of the cell; used also as a word termination, as in erythroblast, etc.
Source:
PAC, 2012, 84, 1113. (IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)) on page 1134 [Terms] [Paper]