Sometimes, words don't mean what it seems like they should mean. Take this Synonym of the Day, for instance.
The only reason that I got the right answer when I saw it on FB was because I could eliminate the other two possibilities.
I know that I have come across erstwhile in my reading, but apparently, I never really knew what it meant. To me, it seemed like it should mean something like notably worthwhile.
Although it is synonym for former, it doesn't always substitute exactly; here is how thesaurus.com describes its usage.
The adjective former means, broadly, earlier in time (during a former stage in the proceedings) or, of two things in succession, earlier in order (Our former manufacturing process was too costly). Erstwhile isn’t a viable synonym in these cases, but it does overlap in meaning with former in phrases like the former president, a former dancer, former members, her former husband, or my former home, where former refers to someone or something in terms of what they at one time were, but no longer are.
If I understand correctly, one could use erstwhile quite often in place of former.
While I have your rapt attention (heh heh), permit me to make another slight grammar quibble after my recent lie/lay post. It is one I see on FB all of the time; I notice it in sports posts, like this one: "We don’t make playoffs without Allen well deserved"
It was a reply to a post about player Allen receiving an accolade, so that phrase, "well deserved," would be understood in the context. Therefore, I will reluctantly not harp in that part despite the lack of a period or other punctuation.
But I can't abide the increasing use of the present tense when either the future or past applies. We wouldn't have made the playoffs is what the writer meant. Is it really so difficult? I am just picking one one example, and to be fair, it was just a quick reply to a post, but I see this in main posts too and all too frequently, by qualified sports journalists.
I close with this although I guess I am not being altogether silent.