supplementary notebook; sub-notebook (for class)
A notebook used alongside a main textbook or lecture notes, often for summaries, exercises, or supplementary material. Wasei-eigo from English 'sub-note'.
wasei-eigo (Japanese-coined English), from sub-note
I'm summarizing the class content in my supplementary notebook.
subnotebook; ultraportable computer
Refers to a small, lightweight laptop, often called a subnotebook or ultraportable in English. Less common than the classroom notebook sense.
At the time, subnotebooks were popular among mobile workers.
Variant with a middle dot; less common but seen in some contexts.
Wasei-eigo from English 'sub' + 'note'. The classroom notebook sense is a Japanese coinage; the computer sense is a direct borrowing of English 'subnotebook'.