heartless

Hard is a related term of heartless.

As a noun hard

is stove, heater; an enclosed space in which fuel (usually wood) is burned to provide heating, usually for cooking.

As an adjective heartless is

without a heart; specifically, without feeling, emotion, or concern for others; uncaring.

Sulky is a related term of heartless.

As adjectives the difference between sulky and heartless

is that sulky is silent and withdrawn after being upset while heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring.

As a noun sulky

is a low two-wheeled cart, used in harness racing.

Heartless is a related term of unconcerned.

As adjectives the difference between heartless and unconcerned

is that heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring while unconcerned is indifferent and having no interest; aloof.

Unemotional is a related term of heartless.

As adjectives the difference between unemotional and heartless

is that unemotional is showing little or no feeling while heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring.

Morose is a related term of heartless.

As adjectives the difference between morose and heartless

is that morose is sullen]], gloomy; showing a [[brood|brooding ill humour while heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring.

As adjectives the difference between ungentle and heartless

is that ungentle is not gentle while heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring.

Heartless is a related term of hardhearted.

As adjectives the difference between heartless and hardhearted

is that heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring while hardhearted is lacking in compassion; cold and pitiless.

Unsparing is a related term of heartless.

As adjectives the difference between unsparing and heartless

is that unsparing is without sparing while heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring.

Severe is a related term of heartless.

As adjectives the difference between severe and heartless

is that severe is severe, harsh while heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring.

As adjectives the difference between heartless and indifferent

is that heartless is without a heart; specifically, without feeling, emotion, or concern for others; uncaring while indifferent is not caring or concerned; uninterested, apathetic.

As an adverb indifferent is

to some extent, in some degree (intermediate between very and not at all); moderately, tolerably, fairly.