This was triggered by a couple of those 1950s newsreel and educational films. Narrators in that era were tiresomely Grammatical and Enunciative. Every phoneme agreed with the dictionary. This film is about engines and this is about mimeographs. Both topics constantly mention cylinders. I would expect the Enunciators to say sillinder, but they said sellinder every time, just like ordinary unenunciative peasants.
Cylinder is unique. Every parallel fails. Other words starting with the same three phonemes follow the normal rules. If two consonants or a written double consonant follows the vowel, the vowel is “short”. If a written single consonant follows the vowel, the vowel is “long”. Greek or Latin or “sciency” words don’t follow the rules.
Sill, silk, silt, silly, all “short”.
Silent, silo, silage, all “long”.
Silent is pretty close to a minimal pair. Cylinder should rhyme.
I can’t think of a good reason for sellinder. If the L tried to velarize the vowel, the first group (sill, silk, silt) should all be sell.
Other words spelled with initial CY are Greek or sciency, so they don’t follow the usual double vs single rule, but all have either the “long” or “short” I sound for the spelled Y.
Cyan, cyber, cycle, cynic, cynosure, cypher, cytokine.
None of them rhyme with cylinder.
Polistra's Mill 