Within the Jewish people's tradition of the Otsarim, Oham is the "Otsar" or collection or Catalog of Hebrew patterns.
Look at What Oham is not.
Now, it is not a common or usual collection: it is a huge pattern collection.
'Oham' is the shortened word of 'Otsar hamishqalim ', אוֹצַר הַמִּשְׁקָלִים, namely "Collection of patterns".
'Otsar' is a noun, the first word in Pro 21:20. It means "treasury", "collection".
And 'mishqal' is a noun that means "pattern": see Ezr 8:30 or Jer 51:20.
[It also means "weight"]
The English equivalence for Oham is The Hebrew Schemary.
It could also be called "The Hebrew pattern Catalog".
Oham is useful and extremely helping disregarding of what kind of grammar, handbook, dictionary, course... you are dealing with.
The same as such tools as pliers, hammer and most of other basic tools that are used in and suit to most machines and engines disregarding of which their builder, manufacturer or trademark is.