1. Too small to be visible to the naked eye

See also: seeable, visible

• unbeloved
• unbelt
• unbelted
• unbend
• unbendable
• unbending
• unbeneficed
• unbent
• unbiased
• unbiassed
• unbidden
• unbigoted
• unbind
• unbitter
• unbleached
• unblemished
• unblended
• unblessed
• unblinking
• unblinkingly
• unblock
• unbloody
• unblushing
• unblushingly
• unbodied