From the given options, select the word which will correctly and adequately replace or substitute the expression.

"Someone who is physically or psychologically dependent on the habitual intake of a drug or substance." – 

Addict

The correct word is addict. It means "someone who is physically or psychologically dependent on the habitual intake of a drug or substance." The other words do not have the same meaning.

• Adenoidal refers to a condition in which the adenoids, which are two small masses of tissue at the back of the throat, are enlarged.
• Adamant means "firmly resolved or unyielding."
• Adhere means "to stick or hold fast to something."