Similar words
fisura
rendija specifically means a narrow gap or slit, like a crack under a door; fisura is more about a structural crack or fissure, in a wall or a bone.
Similar in other languages
Portuguese
trinca
trinca is the Portuguese word for the same thing — both mean "crack."
Practice
1 What does rendija mean?
crack
2 Fill the gap: Entra luz por la ___.
Full sentence: Entra luz por la rendija. (Light comes through the crack.)
3 Which fingerprint chart matches rendija?
rendija: neutral register, academic frequency, general domain, neutral connotation.