adjective
1.
Synonyms: baseless , foundationless, gratuitous, groundless, uncalled-for, unfounded, ungrounded, unwarranted
Related Word: reasonless, unjustifiable, unsupportable
2.
extremely deep
the bottomless sea
Synonyms: abysmal, fathomless, plumbless, plummetless, soundless, unfathomable; compare deep 1
Related Word: endless, infinite