Heath vs Undefined - What's the difference?

As a proper noun heath

is .

lacking a definition or value.

(wikipedia heath)

A tract of level uncultivated land with sandy soil and scrubby vegetation; heathland.

* ~1602 , William Shakespeare, Macbeth , Act I, scene I:

*:1. Where the place?/2. Vpon the Heath /3. There to meet with Macbeth

Any small evergreen shrub of the family Ericaceae .

* 1974 , (GB Edwards), The Book of Ebenezer Le Page , New York 2007, p. 258:

There was nobody living in Jim's old house, and some of the windows was broken; but there was heath growing back and front.

# Many of the species in the genus Erica

# Many of the species in the genus Cassiope

# Both species in the genus

# Any of the species in the genus

(label) Certain butterflies and moths

# The palaearctic species of Coenonympha , a genus of brush-footed butterfly

## , native to Europe, Asia except tropical India and Indochina, and Northern Africa, the small heath

## , native to Europe, Asia except tropical India and Indochina, and North America, the large heath

# , the heath fritillary

* The word heaths may describe multiple disconnected heathlands.

* heather

(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