Type of suffix: adjectival
The French suffix -issime can is added to adjectives to make stronger adjectives - it means "very" or "extremely." There are only a few French words that end in -issime and they are usually quite rare:
bellissime - very beautiful
(added to belle - beautiful)
éminentissime - most eminent (to a cardinal)
(added to éminent - eminent)
excellentissime - very excellent
(added to excellent - excellent)
grandissime - very big
(added to grand - big)
gravissime - extremely serious
(added to grave - serious)
illustrissime - very illustrious
(added to illustre - illustrious)
rarissime - extremely rare
(added to rare - rare)
révérendissime - most reverend (to an archbishop)
(added to révérend - reverend)
richissime - extremely rich
(added to riche - rich)
sérénissime - most serene (to royalty); (historically) Venetian
(added to serein - serene)
There is also one noun that takes the suffix -issime:
généralissime - generalissimo, top general, general in charge of other generals
(added to général - general)
The suffix -issime is the Frenchified version of the Italian suffix -issimo, but there are also a few words in French that keep the original form. Note that with the exception of bravissimo, they are all adverbs and all relate to playing music:
bravissimo - bravo (exclamation)
dolcissimo - very sweetly
fortissimo - very loudly
pianissimo - very softly
prestissimo - very quickly
Le Grand Robert makes an interesting remark in its -issime entry:
Ce suffixe, parfois sous la forme italienne -issimo, a été mis à la mode dans les années 1950-1960 (cf. Snobissimo, de P. Daninos) et sert à former des adjectifs plus ou moins plaisants.
(…) Paris continue sa marche en avant vers le Paris parissime, capitale superspirituelle (…) Jacques Perret, Bâtons dans les roues, p. 25.
