I think a lot about this. It's funny how there are certain domains of language, familiar to all native speakers, but that you are simply not likely to learn as an adult language learner, at least not without diligent and focused study.
I live and work in a foreign country, and have a modest but functional grasp of the language here. Which is to say, I know how to say 'sustainability', 'union-negotiated collective agreement', and 'offensive conduct in the workplace'.... but if you asked me the words for 'cedar', 'robin', 'pond', or 'linen' I would be struck dumb. And yet presumably every ten year old I walk past in the street would know those words as comfortably as I knew them in English as a ten year old in England.
Words like cedar/robin/linen come from either the physical or cultral environment that I (as a Chinese) wasn't exposed to when I was a child. Cedar and robin are all species native to Europe, and I guess they also appear in many Western fairy tales or historical stories.
Also, both because of the familiarity and how English form words, English assign very specific non-compound words to them (rather than "xxx tree/bird"), making it more difficult for people from a completely different language family to learn them.
But of course this is not only English. In Chinese a child is taught to act 孝 (filial piety, respect and obedience to parents) and know how your uncles 舅 (mother's brother) 伯 (father's elder brother) 叔 (father's younger brother) relate to your parents. I'm sure it's OK for a foreign learner not to master them.
When you're a foreigner learning a language your experience is mostly from reading. There are words, however, that are much more common at home and in spoken language. So you'll probably never learn the words that a 10 year old kid knows.
> if you asked me the words for 'cedar', 'robin', 'pond', or 'linen' I would be struck dumb. And yet presumably every ten year old I walk past in the street would know those words as comfortably as I knew them in English as a ten year old in England.
Indeed. I'm American but my family has spoken German in the USA uninterrupted for 200 years. I speak German with my kids. But there's a children's song called Alle Vögel sind schon da and another called die Vogelhochzeit that I listen to with my kids, and it's just a litany of bird species I do not know but, being in a kid's song, I assume means they are common words for German kids.
When I look them up, the English words are ones I've heard and know from context are birds, but I couldn't tell you what they are like, and I would never use the word in English when asked about birds. My go-tos would be mockingbird, cardinal, hummingbird...ones I see in my backyard and have seen my entire life.
It's kinda funny. My life switched to English when I was around 18 and, while my family still speaks my native language exclusively, everything I've learned since then I don't know how to say it in my native language.
Just earlier I was talking to them, trying to say "when life gives you lemons" and being unable to find an equivalent phrase. I hope they understood my lemons reference regardless.