What is "plastid"

Plastid \Plas"tid\, Plastide \Plas"tide\, n. [Gr. ?, ?, a creator.]

1. (Biol.) A formative particle of albuminous matter; a monad; a cytode. See the Note under Morphon. [Archaic]
   --Haeckel.

2. (Bot.) any of several types of minute granules found in the protoplasm of vegetable cells, having their own membrane, robosomes, and DNA. Among plant cells the most common are chloroplasts, which contain the chlorophyll and the photosynthetic machinery of the cell. They are divided by their colors into three classes, chloroplastids, chromoplastids, and leucoplastids.

1876, from German plastid, coined by Haeckel from Greek plastos "molded, formed" (see plaster) + -id.

n. (context biology English) Any of various organelles found in the cells of plants and algae, often concerned with photosynthesis

n. any of various small particles in the cytoplasm of the cells of plants and some animals containing pigments or starch or oil or protein

Plastids are double membrane bounded organelles mostly containing pigments and are capable of manufacturing and storing chemical compounds used by the plants. The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a major double-membrane organelle found, among others, in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell. They often contain pigments used in photosynthesis, and the types of pigments present can change or determine the cell's color. They have a common evolutionary origin and possess a double-stranded DNA molecule that is circular, like that of prokaryotic cells.