indisposed to action or exertion; lacking in energy; lazy; indolent

a sluggish disposition.

not acting or working with full vigor, as bodily organs

a sluggish liver.

slow to act or respond

a sluggish car engine.

moving slowly, or having little motion, as a stream.

slow, as motion.

slack, as trade, business, or sales.

noun

dullness , hebetude , languidness , languor , lassitude , leadenness , listlessness , stupor , torpidity , torpor , idleness , indolence , shiftlessness , sloth , slothfulness , sluggardness , inertia , lethargy