The thesauri and dictionaries offer marvelous help with some of these.
Adapted from Döderlein's Hand-book of Latin Synonymes:
- Interficere and perimere are the most general expressions for putting to death, in whatever manner, and from whatever motive, but interficere as a usual, perimere as an old, forcible, poetical expression.
- Interimere involves the accessory notion of privacy, as to remove out of the way; [Cic. Tusc. v. 20. Dionysius alterum jussit interfici, quia viam demonstravisset interimendi sui.]
- necare, that of injustice, or, at least, cruelty, to murder. [Curt. ix. 7, 8. Boxum protinus placuit interfici; Biconem etiam per cruciatus necari.]
- Occidere, jugulare, trucidare, obtruncare, percutere, denote a sanguinary death-blow; occidere means by cutting down, especially the business of the soldier in honorable open battle;
- jugulare, by cutting the throat or neck, or rather by a skilfully-directed thrust into the collar-bone, especially the business of the bandit, after the pattern of the gladiator;
- obtruncare means to butcher, massacre, and cut to pieces, after the manner of the awkward murderer; [Sallust. Fr. Cæteri vice pecorum obtruncantur; so that you may see a mangled mass of limbs, as in the heap of slain in a battle.]
- trucidare, to slaughter as one would a steer, after the manner of the blood-thirsty miscreant, who, without meeting with resistance, plays the hero on the defenceless; [Tac. Hist. Juberet interfici; offerre se corpora iræ; trucidaret.]
- percutere, to execute, as a mere mechanical act, after the manner of the headsman, or other executioner of a sentence of condemnation, or, at least, of a death-warrant. [Cic. Cat. iv. 6. and Rosc. Am. 34. Cujus consilio occisus sit invenio; cujus manu percussus sit non invenio.]
And adapted from Smith's Copious and Critical English-Latin Dictionary:
- interficio (most general term).
- cædo (to cut or beat, whether to death or not; to kill by wounds or blows). To slay.
- neco (by wicked and cruel means; as, assassination, poison). To murder.
- occido (to cut down, esp. in battle). To slay.
- trucido (to kill violently and ruthlessly). To butcher.
- interimo (to do away with, cut off). To destroy.
- obtrunco (to cut down, esp. in the way of murder or assassination). To slaughter.
I must say, as a spoken-Latin advocate, that, while Latin can be frustrating when you want to talk about things like a malfunctioning ATM or the difficulty one has signing up for a user account, when you're as angry a person as I am it's quite useful to have so many words with which to imagine people's violent ends.