The authors agree that the surname derives from the Latin personal name Marinus, read as a variant of Marius ("Mario"), of probable Etruscan origin. To this is added an association by popular etymology with the Latin adjective marinus, which designates one who lives beside the sea or comes from maritime areas. In time, that personal name became a surname.

E. De Felice notes that some surnames of this family also reflect place names such as Marino or Marini, frequent especially in central and southern Italy. He identifies the form Marini as characteristic of the north and of Tuscany, while Marino predominates in the centre and the south.

E. De Stefani adds that the spread of the name in certain areas was favoured by the cult of Saint Marinus of Caesarea. He notes that the form Marin, with the loss of the final vowel, is typical of north-eastern Italy, in the regions of Veneto, Friuli-Venezia Giulia and Trentino-Alto Adige, and is documented in Carnia —the mountainous area of northern Friuli, in the province of Udine— from the end of the 15th century.

E. Costantini specifies the distribution in Friuli-Venezia Giulia: the form Marini is concentrated especially in Gemona and appears also in Udine, Gorizia, Tolmezzo, Pordenone, Cormòns, Monfalcone, Varmo, Grado and Tavagnacco. The form Marìn, more widespread in Veneto, has a presence also in Spilimbergo, Udine and Pordenone, recorded at Grado from 1592.