Blind, sightless, purblind mean lacking or deficient in the power to see or to discriminate objects.
Blind is used to imply absence or deprivation or gross restriction of the power of vision, either by congenital defect or as a result of disease or of an injury to the organs of vision.
It is as often employed in an extended sense, especially as implying a lack of the mental, moral, or spiritual vision essential to the perception or discernment of what actually exists or what is really true.
Blind is also applicable to things devoid of intelligence or of ability to know whither they are moving or tending or to acts, emotions, and attitudes which are the result of or which produce mental, moral, or spiritual blindness or to something (as a space or a structure) that is so dark or obscure or obstructed that one cannot see through, into, or around it.
Sightless is sometimes the preferred term when permanent total blindness is implied.
Purblind is disused in the sense of totally blind, but it persists in the sense of nearly blind, or without sight enough to do one’s work or make one’s way successfully.
More usually, purblind implies the imperfection or even the absence of mental, moral, or spiritual vision and usually connotes obtuseness or shortsightedness that comes from ignorance, stupidity, or indifference.