Something you cannot do without is indispensable. Alternatively, in legal terms, it could be a sine qua non, which is an essential component of an agreement. A without which nothing.
No, the word "without" is not a determiner. It is a preposition that is used to show the absence or lack of something.
youre subconsciously doing something
Impermeable.
arbitrary
A single word that can be defined as (or otherwise signifies)'too important to be done without' is 'necessary.' When and where something is 'too important to be done without,' that same something is 'necessary.'
metaphor
Unexpected?
Peripheral (To look at something at the edge of one's vision or using peripheral vision)
Well, it means someone or something does something without any warning.
the meaning of the word in is to go into. Or to be inside something.
The word for something that gives out light without heat is "luminescent." The process is called luminescence, and the light produced is often referred to as "cold light."
The root word of "lackluster" is "lack," which means to be without something that is needed or wanted.