Originally: (esp. of suffering) not mitigated or rendered more tolerable by something. Later also more generally: unredeemed by variation…

(un-, prefix1 affix 3.)

Having no strongly marked effects, characteristics, etc.; undefined, indefinite, vague. Now rare or merged in sense B. 4.

Without variety; monotonous.

(un-, prefix1 affix 1.)

transferred. Without any prominent mark or point of interest; uninteresting.

Without a clue, trackless.

(un-, prefix1 affix 2.)

(un-, prefix1 affix 2.)

Without attributes.

Without a face; lacking identity; anonymous, characterless.

Having typical features and few unique ones; formulaic or standardized.

In extended use: designating something obtained or produced quickly and easily, with relatively little expense, effort, or thought; (hence)…