Single malt is a grain distillate from a single distillery. One way of describing this is a signature distillate made from a single type of malted grain from a particular distillery not mixed with anything else, be it a neutral grain alcohol spirit or distillates from another distillery. This can however be a bottle that is made from the blending of multiple barrels of the same spirit from the same distillery. There is also no legal limit on how many barrels this could be in total and there are some releases that are quite large.
It is usually meant to convey that this is a singular personality of a whiskey as it were rather than a blend.
Blended whiskies in and of themselves can be quite excellent and combine the characteristics and high points of disparate individual malts.
Blended malt/whiskies have however suffered because of the many examples out the re whose primary goal was to produce a cheaper to market product than a quality one.
A delicate variation/iteration from its sibling the Original Ten with an interesting, subdued yet flavourful melange. Also, Damn cheap compared on both age and quality in the Scotch arena.
A simply amazing Irish Whisky. A singular blend of 25 separate expressions into a single bottling, each adding its voice to the choir. Ther is no better Irish Whisky on the market right now in my opinion.