groundless

As a letter s

is the letter s with a.

As an adjective groundless is

without any grounds to support it; baseless.

Impalpable is a related term of groundless.

As adjectives the difference between impalpable and groundless

is that impalpable is not able to be perceived by the senses (especially by touch); intangible or insubstantial while groundless is without any grounds to support it; baseless.

Groundless is a related term of unsuitable.

As adjectives the difference between groundless and unsuitable

is that groundless is without any grounds to support it; baseless while unsuitable is not suitable; unfit; inappropriate.

As adjectives the difference between groundless and meritless

is that groundless is without any grounds to support it; baseless while meritless is without merit.

As adjectives the difference between arbitrary and groundless

is that arbitrary is (usually|of a decision) based on individual discretion or judgment; not based on any objective distinction, perhaps even made at random while groundless is without any grounds to support it; baseless.

As a noun arbitrary

is anything arbitrary, such as an arithmetical value or a fee.

As adjectives the difference between groundless and untenable

is that groundless is without any grounds to support it; baseless while untenable is not able to be held, as of an opinion or position; unholdable, indefensible.

As adjectives the difference between groundless and undefined

is that groundless is without any grounds to support it; baseless while undefined is lacking a definition or value.

As adjectives the difference between groundless and ungrounded

is that groundless is without any grounds to support it; baseless while ungrounded is not grounded.

As a verb ungrounded is

(unground).

As adjectives the difference between unprovoked and groundless

is that unprovoked is happening without provocation or motivation while groundless is without any grounds to support it; baseless.