lethargy

As a verb languish

is to lose strength and become weak; to be in a state of weakness or sickness.

As a noun lethargy is

a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns.

As a noun lethargy

is (pathology) a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns.

As an adjective dull is

lacking the ability to cut easily; not sharp.

As a verb dull is

to render dull; to remove or blunt an edge or something that was sharp.

As a noun lethargy

is (pathology) a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns.

As an adjective tiresome is

causing fatigue or boredom; wearisome.

Slothfulness is a synonym of lethargy.

As nouns the difference between lethargy and slothfulness

is that lethargy is a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns while slothfulness is the state or quality of being slothful.

As nouns the difference between asthenia and lethargy

is that asthenia is weakness; loss of strength while lethargy is a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns.

As nouns the difference between deadpan and lethargy

is that deadpan is a style of comedic delivery in which something humourous is said or done while not exhibiting a change in emotion or facial expression while lethargy is a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns.

As an adjective deadpan

is deliberately impassive or expressionless (as a face or look).

As a verb deadpan

is to express (oneself) in an impassive or expressionless manner.

As an adjective subdued

is conquered; overpowered; crushed; submissive; mild.

As a verb subdued

is past tense of subdue.

As a noun lethargy is

a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns.

As nouns the difference between lethargy and excitement

is that lethargy is a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns while excitement is the state of being excited (emotionally aroused).

As nouns the difference between weakness and lethargy

is that weakness is the condition of being weak while lethargy is a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns.

Inertia is a synonym of lethargy.

As nouns the difference between lethargy and inertia

is that lethargy is a condition characterized by extreme fatigue or drowsiness, or prolonged sleep patterns while inertia is the property of a body that resists any change to its uniform motion; equivalent to its mass.