aimless
The word "aimless" is an adjective. It describes something or someone lacking direction or purpose.
purposeless
one word meaning lacking detail depending on the context of its use would be "spacey." as in "that explanation was kinda spacey." ~VAGUE is a good word meaning "Lacking Detail"~
There are several. One is ne'er-do-well
Words that mean 'lacking enthusiasm' are lackadaisical or apathetic.
The word "colorless" includes a suffix ("-less") that means lacking or without.
The word you are looking for is "ridiculous."
lifeless, sluggish
The word in Greek is Idiotes meaning a person lacking in professional skil
According to Webster's Dictionary the word inane can be defined as empty or insubstantial. It further describes the meaninng to be lacking significance, meaning or point, silly.
The root word is passion.Related Information:Dis (prefix meaning lack of/not) + passion (root word) + ate (suffix meaning state of)Resulting in dispassionate meaning a state of lack of passion.
You would add the suffix -less meaning without or lacking, to make "senseless."