Definition of: unit modifier

A conventional or improvised compound used adjectively before a substantive. Examples: blue-green algae, bitter-sweet chocolate, suit-coat pattern, situation-comdey plot, storm-window installation, contour-plowing method, most-favored-nation clause. ♦ The use of the hyphen in the unit modifier is to avoid ambiguity in a word sequence where the relationship is not immediately apparent from context: The house had faded red-brick walls (faded walls of red brick, not faded red walls of brick). The hyphen here is to be considered a nonce use and not as a spelling form or variant.