I need to learn what?

My Xinhua gives ma1 (in the form of the compound 蚂螂) as a regionalism for 蜻蜓 (qīngtíng). Strangely, it only has the leech but not the ant compound at ma3 (the ABCE ECCE meanwhile directs from the single character to the 'bound form' ant compound only, though the leech compound is there on the same page, just simply later in the alphabetical ordering). Ma4 as some sort of grasshoppery thingy I can live with.

Anyway, it's always interesting flicking through dictionaries - my eye fell upon 'grass widow/widower' as I was checking for 'grasshopper' (none) versus 'locust' (included) entries in the E-C section of the ECCE, and I wasn't quite sure what the term meant. The definition if not meaning given in Chinese is 离了婚或分居的女子/男人 líle hūn huò fēnjū de nǚzǐ/nánrén), but I prefer the clearer (and likely more correct, general, yet nonetheless "exacting") definition in the Oxford Advanced Learner's: "a woman whose husband is away from home for long periods of time". (The ECCE's perhaps overlaps a little too much with 'divorcee' and "separ[at]ee" IMHO (latter's a word I just made up , versus 'They've separated' )).