"Obsession" in the Twelve and Twelve and Big Book:

 In our literature this word almost always means the obsession to drink. The 12 & 12 has many passages in which the solution to the problem involves removing, relieving, etc this obsession. This is, in fact, the second most common term for the solution other than 'recovered.' A few other uses related to alcoholism from the Big Book are shown at the bottom.

12 & 12:

“A.A.’s Twelve Steps are a group of principles, spiritual in nature, which, if practiced as a way of life, can expel the obsession to drink and enable the sufferer to become happily and usefully whole.”
Page 15, Foreword

“It is truly awful to admit that, glass in hand, we have warped our minds into such an obsession for destructive drinking that only an act of Providence can remove it from us.”
Page 21, Step One

“Our sponsors declared that we were the victims of a mental obsession so subtly powerful that no amount of human willpower could break it. There was, they said, no such thing as the personal conquest of this compulsion by the unaided will.”
Page 22, Step One

“We stand ready to do anything which will lift the merciless obsession from us. [Obsession to drink]’
Page 24, Step One

“Having reduced us to a state of absolute helplessness, you now declare that none but a Higher Power can remove our obsession [to drink].”
Page 25 Step Two

“Relieved of their alcohol obsession, their lives unaccountably transformed, they came to believe in a Higher Power, and most began to talk of God.”
Page 28, Step Two

“The fact was we really hadn’t cleaned house so that the grace of God could enter us and expel the obsession [to drink].”
Page 32, Step Two

“But when I became willing to clean house and then ask a Higher Power, God as I understand him, to give me release, my obsession to drink vanished. It was lifted right out of me.”
Page 63, Step Six

“It is plain for everybody to see that each sober A.A. member has been granted a release from this very obstinate and potentially fatal obsession. So in a very complete and literal way, all A.A.’s have ‘become entirely ready’ to have God remove the mania for alcohol from their lives.”

“As they are humbled by the terrific beating administered by alcohol, the grace of God can enter them and expel their obsession.”
Page 64, Step Six

“If that degree of humility could enable us to find the grace by which such a deadly obsession [to drink] could be banished, then there must be hope of the same result respecting any other problem we could possibly have.”
Page 76, Step Seven

“We found that we were totally unable to be rid of the alcohol obsession until we first admitted that we were powerless over it.”
Page 107, Step Twelve (summarizing Step 1)

Different Uses of Obsession:

Big Book:

“Once this malady [alcoholism] has a real hold, they are a baffled lot. There is the obsession that somehow, someday, they will beat the game.”
Page 23, There is a solution

“The idea that somehow, someday he will control and enjoy his drinking is the great obsession of every abnormal drinker. The persistence of this illusion is astonishing.”
Page 30, More About Alcoholism

“There was an insistent yearning to enjoy life as we once knew did and a heartbreaking obsession that some new miracle of control would enable us to do it.”
Page 151, A Vision For You

“He [Dr. Bob] told how he lived in constant worry about those who might find out about his alcoholism. He had, of course, the familiar alcoholic obsession that few knew of his drinking.”
Page 155, A Vision For You

12 & 12:

"Another [person] may develop such an obsession for financial security that he wants to do nothing but hoard money."
Page 43, Step Four

“Most of us would declare that without a fearless admission of our defects to another human being we could not stay sober. It seems plain that the grace of God will not enter to expel our destructive obsessions until we are willing to try this.” (Because of the plural used here, and given the context, 'obsessions' is probably used here to mean defects of character as well as the alcohol obsession)
Page 56-57, Step Five