I'll explain how I use all those terms.

Intimidatory downvoting: Downvoting whose purpose is to discourage people from expressing certain kinds of views on LW by the threat of massive karma loss. (In particular, the threat of much more than they would lose just from having their comments expressing those views downvoted.)

Retributive downvoting: Downvoting whose purpose is to get back at someone who has annoyed or upset you, or whom you don't like for some other reason.

Block-downvoting: Largely-indiscriminative downvoting of a user's comments, whatever the reason. (I might also use the term to describe downvoting everything in some conversation, though I might not because it isn't standard terminology.)

Karmassassination: Large-scale downvoting whose aim is to reduce a particular user's karma score, for whatever reason (could be retributive, could be because you've nothing personal against them but think, after careful reflection, that it would be best for LW if they left, etc.).

I dislike intimidatory downvoting because (1) it's unreasonably unpleasant for the victim, (2) it seems like an attempt to exercise more power over what views are expressed on LW than the karma system is really meant to enable, (3) it distorts the per-comment information karma scores are meant to provide (expressed not only in the scores themselves but in thread ordering), and (4) because most users will avoid it on account of #1 and #3, it gives extra influence to those who care less about the LW community as a whole and extra importance to opinions on topics that push those people's buttons.

[EDITED to add: It occurs to me that it's possible that when not explicitly prompted to distinguish carefully between these terms, I may actually use them less carefully. I don't think so, though. I don't think I've actually used, as opposed to quoting others' use of, the term "karmassassination", which I find ugly. Though I suppose maybe an ugly thing deserves an ugly word. I've also used the term "mass-downvoting", meaning much the same as "block-downvoting".]

Eugene gets accused of block downvoting, based on the incontrovertible evidence of multiple posters not being terribly fond of him.

This is not at all a reasonable summary of what was going on there. A specific reason for focusing on Eugine was given, and Eugine's continued lack of comment at this point is not helping matters. (That's unfortunate because I'd much rather believer that he isn't doing this.)

You judge that he is not only guilty of block downvoting, but specifically targeting feminists because of his reactionary politics.

Not necessarily feminists per se, but the fact is that almost all the people who have experienced mass downvoting are people who have argued against traditional sex or gender roles.

shminux has been block downvoted, and once made a reply to a comment espousing a neoreactionary view of gender.

Shminux made a (somewhat insulting, not necessarily productive) comment, and the downvoting experience started off shortly thereafter.

view of gender. Therefore, as the author of said comment, the implication is that I must have waited for "a few days" and then systematically downvoted all (or just most?) of shminux's comments. Because the comment did something to "aggregate" (aggravate?) me or maybe just out of solidarity with other reactionaries (because I guess that's what we do now?).

Adele_L said nothing at all about you being involved in any way with any block downvoting behavior.

And the idea of using mass downvoting to harass people I dislike is the kind of passive-aggressive thought policing nonsense which made me stop being a progressive in the first place (seriously, using anonymous voting to shut someone up by making them seem unpopular... how is that supposed to be right wing?).

Let me tentatively suggest that there's nothing intrinsically "right-wing" or "left-wing" about such behavior. It may be manifesting itself in a specific political framework, but very likely is more a function of the individual or individuals engaging in the behavior than saying much about their political alignment.

But politically motivated mud-slinging and invocation of the mods to remove people you disagree with is absolutely beyond the pale.

The primary invoking of the mods I've seen here has been to actually take a look and see who the downvotes are coming from. That's a pretty distinct situation.

I have never suspected you, and I am not accusing you of anything. Comments can be aggravating to people who are not the direct recipient.

An amount which is large to me, but thanks for trivializing my willingness to sacrifice.

While I'm genuinely not sure whether that's tongue-in-cheek or not, either way I'd rather go to Reddit to witness such tragicomedies and not see this community, too, devolve into adolescent internet-points-bickering. I admit that I dig the entertainment value (and the bait is strong), but as the proverb goes, let's keep this place free from apotheosing imaginary constructs. Instead, right this way is a better place to bravely martyr yourself for the public good.

It is my estimation that none of the people around here whose approval is typically sought will actually judge you by your karma score in any significant sense, as opposed to by being impressed with the content of your comments, or your posts in Main. There are plenty of low karma commenters whose contributions I respect, and some high karma commenters whose I don't. YMMV.