A mammothreptus is a hefty volume, a huge tome
Mammothretus is a word that designates bulky book, fat, heavy and of little value. The origin of this word is very curious. It comes from the Greek via Latin.
The Spanish Royal Academy defines “mamotreto” (latin mammotrectus/mammothreptus) as "hulk, very bulky book or file, especially irregular and deformed".
Sebastian de Covarrubias, in his Treasury of the Castilian language (1611) defines it as "Big book in volume about frivolous materials and of little fruit." Equivalent also therefore a “huge tome”.
It is considered that derives from the late Latin "mammotrectus" and this from "mammothreptus" which comes from the late Greek μαμμόθρεπτος.
The Greek-latin word literally means "raised at the teat", "suckling longer due", "sucker", without the connotation it has in colloquial and vulgar, and also "raised by his grandmother" (if you drift of μἀμμη, mamme, mother, grandmother, and θρεπτὁς, threptos, fed, bred, of τρέφειν, trefein, feeding) and perhaps better "raised by a nurse".
In any case concerns a fat kid, beefy, big guy, that is whether by excess breast and for a long time and as if he is raised with much attention, as usually do grandmothers and nurses.
Now, what has happened for that this word, that appoints a chubby child, pass to refer to a tome, too fat, heavy and often of little value?
It cites and documents the following explanation. In the fourteenth century, a certain Giovanni Marchesini, Franciscan friar, gave this name to his biblical interpretation manual "Mammotrectus super Bibliam ", a glossary about 1,300 terms to help young friars. There is a manuscript of 1375 and since then it was printed many times in the fifteenth and sixteenth centuries.
The term would mean "food" or "nurse" of the Bible. The title could come from a passage of St. Augustine in his "Enarrationes in Psalmos", In eumdem Psalmum 30, Sermo 2, 12 [v 15.]:
If you look at the man and want to imitate him and depend on him, still want to feed on milk, and you become a mammothreptus, as is said of the children who breastfeed for a long time, so you should not .... The nurses will do this to mammothreptis , put something bitter on her nipples, so that children do depart upset with chest and feel to the table. So say, "I said, waited on you, Lord, Thou art my God"
Si attendis adhuc hominem, et cum quaeris imitari, et ex illo pendere, adhuc lacte vis nutriri; et fies mammothreptus, quales dicuntur pueri qui diu sugunt, quod non decet... Faciunt enim hoc nutrices mammothreptis, ut aliqua amara ponant in papillis suis, quibus offensi parvuli ab ubere resiliant, et ad mensam inhient. Ergo dicat; Ego autem in te speravi, Domine, dixi: Tu es Deus meus.
What Giovanni Marchesini will mean is that just as children need mother's milk, the young monks need the elementary and primary food of his manual or dictionary. The dictionary is like a mother or wet nurse.
He self explains in the preface that so as in the same way that the teacher directs the steps of the nursery, so his work can be called "Mammotrectus":
And because it creates custom the work of the teacher who directs the steps of the nursery, may be called Mamotreto
“et quod morem gerit talis decursus pedagogi qui gressus dirigit parvulorum, Mammotrectus poterit appellari”.
Although this "mammotrectus" was fatter than other manuals used by the students, yet the term didn’t had the meaning of "big book" that then acquired in student jargon.
But one "big book" does not have to be heavy or dull. No doubt thousands of Argentines and Spanish people remember with sympathy and affection the famous encyclopedia and educational television series "The Big Book of Petete ". Even the book of Marchesini , that gives rise to this word, should be useful for many generations of monks, judging by the many impressions he had.