Substrate (noun)

1. A surface or substance on or from which something grows, develops, or is attached.
2. A material or substance used as a basis for a layer or coating.

Origin:

Late 19th century: from german substrat, from latin substratus "something laid underneath", from sub- "under" + stratus "spread out".

Examples:

1. The plant found a suitable substrate to grow in the soil.
2. The substrate of the circuit board was made of fiberglass.
3. The substrate used for the photovoltaic cells was specially treated silicon.
4. The substrate was carefully prepared to ensure the adhesion of the paint.
5. The substrate of the painting was a canvas.