'non-bulbous' originates from modern English as a compound of the prefix 'non-' and the adjective 'bulbous'; 'non-' ultimately derives from Latin 'non' meaning 'not', and 'bulbous' originates from Latin 'bulbus' meaning 'bulb (onion)'.

'bulbous' comes from Latin 'bulbus' (meaning 'bulb, onion') via Old French 'bulbe' and Middle English forms; the negative prefix 'non-' was attached in modern English to form the compound adjective 'non-bulbous'.

Initially, 'bulbous' related directly to a 'bulb' (a rounded, bulb-like organ) and by extension came to mean 'rounded or swollen in shape'; 'non-bulbous' therefore developed the straightforward negated meaning 'not having that rounded/swollen shape'.