In the field of cryptanalysis, what is meant by a "rubber-hose" attack?

Making logical assumptions about plaintext from ciphertext describes a ciphertext-only or known-plaintext cryptanalytic attack, which is a mathematical technique, not coercion.

The rubber-hose attack is named as dark humor for physically coercing - such as beating someone with a rubber hose - an individual into disclosing their password, passphrase, or encryption key. Unlike computational attacks, it targets the human holding the secret rather than the algorithm itself. This highlights that the human element is often the weakest link in any cryptographic system, regardless of how mathematically strong the algorithm is.

Forcing a key stream through hardware acceleration such as an ASIC describes a brute-force or hardware-accelerated cryptanalysis attack, which targets the algorithm computationally.

A backdoor placed into an algorithm by its creator describes a kleptographic or trapdoor attack, which is a design-level compromise, not coercion of a person.