Spinach vs Undefined - What's the difference?

As a noun spinach

is a particular edible plant, spinacia oleracea , or its leaves.

lacking a definition or value.

(wikipedia spinach)

A particular edible plant, Spinacia oleracea , or its leaves.

Any of numerous plants, or their leaves, which are used for greens in the same way Spinacia oleraceae is.

# Chinese spinach, )

# Malabar spinach (

# New Zealand spinach ()

# water spinach ()

# (label) (various nightshade, legume, and Cucurbitaceae species)

# (Beta vulgaris : chard)

# )

# Lincolnshire spinach (: Good King Henry)

# mountain spinach Atriplex spp.

# )

(wikipedia undefined) (-)

Lacking a definition or value.

(mathematics, computing) That does not have a meaning and is thus not assigned an interpretation.

The result of division by zero is undefined .

* defined