for this anarchist, alienation refers to a very personal sense of disconnection from direct, lived experience.
"direct, lived experience" is obviously a subjective phrase.
for me, (eg) growing my own food, harvesting it, preparing it, and eating it, is just such an experience. while going to a supermarket to purchase some food grown by someone i don't know (using methods i don't know about) a thousand miles away and shipped to my bioregion, is alienating.
but for some, the act of going to the supermarket, choosing what they want, maybe seeing and talking to folks they know, and taking that food home to prepare and eat, is entirely a direct, lived experience. and who could really argue otherwise?
i think the more mediated a given activity is - that is, the more crap/people/processes/institutions/etc that sit between myself and the fulfillment of my needs and desires - the more alienating i find it.
where this ties to my anarchist perspective is regarding my individual autonomy. if i need to rely on crap/people/processes/institutions/etc to meet my needs/desires, i feel both alienated and less autonomous.
alienation is also how i would describe what i feel when i see how different my desires for life are, when compared to most people i come across (even many that i care deeply about).