https://www.collinsdictionary.com/dictionary/...

1. COUNTABLE NOUN

A beaker is a plastic cup used for drinking, usually one with no handle. [British]

2. COUNTABLE NOUN

A beaker is a large cup or glass. [US]

3. COUNTABLE NOUN

A beaker is a glass or plastic jar which is used in chemistry.

https://www.oed.com/view/Entry/16489?redirect...

 a. A large drinking vessel with a wide mouth, an open cup or goblet. (Now chiefly in literary use.)

1348   Acc. Edw. Pr. Wales in Promptorium Parvulorum 35  Magne pecie argenti, vocate Bikers.

1420   in F. J. Furnivall Fifty Earliest Eng. Wills (1882) 45  A becure of seluer.

c1440   Promptorium Parvulorum 35/2   Byker, cuppe [v.r. bikyr], cimbium.

1600   S. Rowlands Letting of Humors Blood vi. 75  Fill him his Beaker, he will never flinch, To giue a full quart pot the empty pinch.

1726   A. Pope tr. Homer Odyssey IV. xv. 117  The Prince a silver beaker chose.

1872   E. A. Freeman Hist. Ess. 14  His cupbearer was carrying..a royal beaker full of wine.

https://www.merriam-webster.com/dictionary/beaker

1: a large drinking cup that has a wide mouth and is sometimes supported on a standard

2: a deep widemouthed thin-walled vessel usually with a lip for pouring that is used especially in science laboratories

https://dictionary.cambridge.org/dictionary/e...

UK a cup, usually with no handles, used for drinking:

She gave the children beakers of juice.

https://www.oxfordlearnersdictionaries.com/de...

 (British English) a cup, usually made of plastic and often without a handle, used for drinking from

She drank from a plastic beaker.

https://www.macmillandictionary.com/dictionar...

​BRITISH a plastic cup with straight sides used for drinking

I wouldn't call a Humpen a beaker, either, but the OED suggests this use of beaker does exist, although 'now chiefly in literary use' (last sample sentence: 1872). Perhaps needs an obs. tag rather than deletion?

A side point: Collins lists a 'large cup or glass' as a US definition, and MW has an entry for 'a large drinking cup that has a wide mouth and is sometimes supported on a standard'. Can a beaker = tankard in the US?

A further side point: all the UK dictionaries (Collins, Macmillan, Oxford Learners, Cambridge) list the (usually) plastic cup as 'British'. Does that mean Americans don't use 'beaker' in this sense? ("The children have a beaker of water with their meal"). There is no tag on beaker - Becher in Leo.

Meanwhile, the OED, so thorough in its evidence for the historical drinking vessel, doesn't list the modern drinking vessel at all!