Leucoplast \Leu"co*plast\ (l[=u]"k[-o]*pl[a^]st), Leucoplastid \Leu`co*plas"tid\ (-pl[a^]s"t[i^]d), n. [Leuco- + Gr. pla`ssein to mold.] (Bot.) One of certain very minute whitish or colorless granules occurring in the protoplasm of plants and supposed to be the nuclei around which starch granules will form.