As Webb’s “Weird Words” hits its 15th installment, here’s a personal question for vocab-loving readers:

Just how many words do you think you know?

For that matter, how many words does the English language actually have?

Wanna take a guess before I tell you?

Well, various online sources indicate the average American is familiar with roughly 20,000 words — though this can double for those with a college education.

As for totals in the language itself: That’s trickier.

Most modest-sized hardcover dictionaries offer about a quarter-of-a-million words. Meanwhile, those hefty, hard-to-handle “unabridged” versions (i.e., the authoritative Webster’s Third) contain roughly twice that.

But then again, I just purchased the 13th Collins English Dictionary, published in 2018. It’s the latest in Britain’s long and prestigious Collins series, whose 1819 inception precedes Noah Webster’s American landmark by nearly 10 years.

Not only does this treasure-trove boast 723,000 words; but more than that, its intro insists that the Collins crew drew on a standing database of — are you ready for this?

Four and a half billion English words.

The all-too-brief “Foreword” (a frequently misspelled word, btw) gives no further info; but I’m virtually certain this stunning figure includes proper nouns — which is certainly case with the current Collins. I was thrilled to see an entry for “Clapton, Eric, b. 1945,” together with three of the legendary ax-man’s bands, plus a handful of his best-known recordings. (“Collins — ya got me on my knees!”)

In any case, a quick perusal of this handsome volume suggests that its principal goal was to include as many words as possible. This is clear not only from the size and selection, but also in its meticulous layout, allowing a vast number of entries per page — all in teensy type that is still somehow perfectly readable.

Open to any two facing pages and you’ll see dozens of words that are not only unfamiliar, but also tough to find in other dictionaries.

With this newest vocab tool in hand, I will likely repeat today’s “lucky-dipping” exercise in future columns; but for our 15th entry of “Weird Words,” here’s a selection from that page (and its facing page) in Collins:

Acetabulum (ass-uh-TAB-yuh-lum, noun) – Cup-shaped cavity on the hipbone that holds the thighbone; also, the “sucker” on a leech, octopus or similar creature.

Acetophenetidin (uh-see-toe-fuh-NET-uh-din, noun) – Alternate name for phenacetin, a painkiller which, according to dictionary.com, has been “withdrawn because of unfavorable side effects.”

Achalasia (ack-uh-LAY-zya, noun) – A medical condition in which the esophagus (Collins: “oesophagus”) will not relax properly, making it difficult to swallow.

Achar (uh-CHAR, noun) – Says Collins: “a spicy pickle made from mango.” While wrapping your head around that, keep in mind: this very British dictionary defines “pickle” as any food “preserved in a vinegar brine.”

Achiote (ah-chee-OH-tee, noun) – Another name for “annatto,” which is in turn defined as a “lipstick tree.” I frankly did not know that was a thing; apparently it’s a shrub of the Americas that produces a bright orange-red seed used for spices, body paint and, yes — lipstick.

Achkan (OTCH-kun, noun) – Long coat for men worn in South Asia.

Ach-laut (OCK-lout, noun) – Here Collins has one of those definitions that induce hopelessness in some readers, as it requires looking up several other words: “the voiceless velar fricative sound that is written as ‘ch’ in Scottish ‘loch’ or in German ‘ach,’ often allophonic with the ich-laut.” Phew! It if weren’t for those examples, I’d have no idea what this meant.

Achoo (ah-CHOO, interjection) – “A representation of the sound of a sneeze (pl, ‘achoos’).” Of course, we all know this, but you don’t see it in a lot of dictionaries!

Reminds me of the corny knock-knock joke in which the person “who’s there” is “OTCH.” (Punchline: “gesundheit.”)

Ach-y-fi (ax-uh-VIE, interjection) – Welsh expression of disgust. Like many Welsh terms, it is easier to say than to spell.

Aciculum (uh-SIK-yuh-lum, noun) – A thin, firm bristle that provides support for the appendages of some worms.

Wait — worms have appendages?? This column has certainly been a learning experience!

Sadly, it doesn’t get us too much closer to 4.5 billion.