You may be shocked by this, but comrade has been in use since the French Revolution, in fact it doesn't mean "friend" like most think - it quite literally means "fellow party-member", someone who is a member of the same party. You, yourself, are comrades with your fellow party members, even if they are not communist. Even if you go to the root of the word, it's Spanish in origin. It's an egalitarian/gender neutral word similar to 'colleague' or "coworker" but effectively it _just_ means "ally" in modern parlence.

Even if you require the link to communism, 'comrade' in the popular sense _is_ used by _socialists_ to describe one another, not just for communists, communists are just a subset ideology of socialism. Similar to anarchists, progressives, and more on the umbrella of "the left", communists are just another branch on the tree of ideologies, and as a branch, they used their mother's language of comradery to describe their fellow party-members and allies.

You can always admit when you are prejudiced by assumptions, you know, so I hope you take an interest in reading this article: https://en.wikipedia.org/wiki/Comrade

Edit:

> The distinctions between socialism and communism are rather academic and irrelevant in the long run

That's quite literally the biggest difference between socialism and communism, the long run. Communists want a communist society as the end-goal of socialism; Socialists do not have that hope, in fact most are not focused on the end goal as we can't ever ascertain what that would look like - so they focus on the values of socialist ideas right now, what we can do now to ensure equality, freedom, and personal rights by protecting all living beings in health and sickness, success and failure. A society of equals first.