The Catechism of the Catholic Church uses the term “disinterested” in five different places. The most relevant instance for most readers of this blog is:
2359 Homosexual persons are called to chastity. By the virtues of self-mastery that teach them inner freedom, at times by the support of disinterested friendship, by prayer and sacramental grace, they can and should gradually and resolutely approach Christian perfection.
The first definition for “disinterested” at Dictionary.com is “unbiased by personal interest or advantage; not influenced by selfish motives,” which would mean that a “disinterested friendship” is a friendship that is not biased by personal interest or advantage, nor influenced by selfish motives. In the context of 2359, the most obvious selfish motive in view would be lust, though any selfish motive will poison friendship. This unbiased and unselfish friendship seems like the sort of love most of us would want from our friends.
However, the second definition for “disinterested” is “not interested; indifferent.” A usage note points out that
Disinterested and uninterested share a confused and confusing history. Disinterested was originally used to mean “not interested, indifferent”; uninterested in its earliest use meant “impartial.” By various developmental twists, disinterested is now used in both senses. Uninterested is used mainly in the sense “not interested, indifferent.” It is occasionally used to mean “not having a personal or property interest.”
And, this confusion infects many people’s understanding of the term “disinterested friendship” in 2359. To many, “disinterested friendship” suggests a friend who is “not interested, indifferent.” Comparison with other usages of the same word in the Catechism, however, demonstrates that this cannot be the sense the authors of the Catechism had in mind.
2649 Prayer of praise is entirely disinterested and rises to God, lauds him, and gives him glory for his own sake, quite beyond what he has done, but simply because HE IS.