Baffo vs. baffi
The Italian words baffo and baffi represent the singular and plural forms of the same root, but they have distinctly different everyday applications. While in English you use the singular word mustache for facial hair, Italian relies on the plural baffi. The singular baffo is reserved for specific physical descriptions, visual metaphors, or popular idioms.
Baffo
B2The word baffo literally translates to a single animal whisker or a single hair from a mustache. Metaphorically, it is widely used to describe a streak, a smudge, or a curved checkmark shape, such as the famous sneaker swoosh logo. It also appears in the common Italian idiom fare un baffo, which means to leave someone completely indifferent to an action or threat.
Il gatto nero ha perso un baffo bianco sul tappeto del salotto.
(The black cat shed a white whisker on the living room rug.)
Con un colpo di pennello il pittore ha creato un baffo blu sulla tela.
(With a brushstroke the painter created a blue streak on the canvas.)
Ho comprato quel paio di scarpe da ginnastica con il baffo rosso.
(I bought that pair of sneakers with the red swoosh.)
Puoi urlare quanto vuoi perché a me la tua rabbia fa un baffo.
(You can yell all you want because your anger does not affect me at all.)
Mi sono guardato allo specchio e ho trovato un baffo grigio.
(I looked in the mirror and found a single gray mustache hair.)
Baffi
A2The word baffi is the plural form and is the standard, universally used Italian term for a mustache or a full set of animal whiskers. It is used whenever you are talking about a person's facial hair styling. It also appears in culinary idioms, most notably da leccarsi i baffi, which describes food that is exceptionally delicious.
Mio zio ha deciso di farsi crescere i baffi e la barba durante le vacanze.
(My uncle decided to grow a mustache and a beard during the holidays.)
Il criceto muoveva i baffi nervosamente mentre annusava il pezzo di formaggio.
(The hamster twitched its whiskers nervously while sniffing the piece of cheese.)
La nonna ha preparato una torta di mele che è una vera bontà da leccarsi i baffi.
(Grandma baked an apple pie that is an absolute lip-smacking delight.)
In quell'epoca storica molti uomini eleganti portavano i baffi a manubrio.
(In that historical era many elegant men wore handlebar mustaches.)
Il gatto randagio si puliva i baffi dopo aver bevuto tutto il latte.
(The stray cat cleaned its whiskers after drinking all the milk.)
Summary
To summarize, use the plural baffi as your go-to word for a man's mustache or an animal's whiskers. You should switch to the singular baffo only when you need to specify one single strand of hair, reference a graphical streak or swoosh, or express complete indifference using the Italian idiom.