Basic Trope: A situation that wasn't intended to be lethal ends with someone dying anyway.
Straight: Alice startles Bob while he is working with a sharp knife. He swings around and unintentionally stabs her.
Exaggerated: Alice startles Bob while he is preparing dynamite to blow up a tree. He swings around and the dynamite explodes, killing several people including Alice.
Downplayed: Bob accidentally stabs or cuts Alice, but not fatally.
Bob is inexperienced with handling dangerous objects.
Bob was drunk.
Alice startled him at an incredibly bad moment.
Inverted: Bob swings around, accidentally deflecting a knife and stopping it from killing her.
The knife almost hits Alice, but she gets out of the way at the last moment.
Bob actually meant to kill Alice, just not in that way at that moment.
...meaning that it hits her in the throat rather than the heart.
The knife connects, but isn't immediately lethal; it's Alice's failure to seek medical care that ultimately kills her.
Parodied: Bob is currently in the fetal position alone in his house because he accidentally killed every single person he came across today in a series of Contrived Coincidences.
Zig Zagged: Bob is conflicted to if he actually wanted to kill her or not. Did some part of him mean to swing the knife in that particular manner or was it the accident he originally thought?
The situation between Bob and Alice does not get lethal.
Bob murders Alice on purpose.
Enforced: "We need a death to create a turning point in the story, but it can't be too tragic. And it can't be a murder because the characters are all friends, and our antagonist hasn't shown up yet." "Let's have Bob accidentally kill Alice. She's the least popular character."
Lampshaded: "Oh, no! I killed Alice!"
Invoked: A Manipulative Bastard wants to kill Alice by proxy, and manipulates Bob into a situation where an accident can happen.
Exploited: Someone uses Bob's accident to convict or blackmail him.
Defied: "I am going to be working with dangerous objects, so above all don't disturb me!"
Discussed: "I'm sure Bob just accidentally turned and swung his knife directly into Alice's heart. This isn't a movie!"
Conversed: "That must have been an accident. Alice and Bob were friends."
Plotted A Good Waste: The writer needs a death to create a turning point in the story, and goes with an accidental death.
Deconstructed: Alice's family suffers from her loss, and Bob is hauled away to Troperville Prison.
Reconstructed: Alice was a single woman and distanced herself from her siblings years ago, so only her friends suffer from her loss. Also, Bob is acquitted when the prosecution can find no evidence that he killed Alice in a premeditated attack. He retains sufficient traumatic memories to avoid anything sharper than his fingernails for the rest of his life, and people come to know him as a very nice man rather than "the guy who accidentally killed Alice".
Back to Accidental Murder, unless some careless novice troper deleted all our examples of that trope.