Lexical Units Anyone?

Definitions for Common Linguistic Units

1) Phoneme: a minimal unit of sound; one might say that phonemes are primitive insofar as they're irreducible to other units. An example is b, I, t in the word, "bit." However, phonemes must not be confused with letters--they are more about variations in sound. See https://www.encyclopedia.com/science-and-technology/computers-and-electrical-engineering/computers-and-computing/phoneme

2) Morpheme: a minimal unit of meaning, and one may distinguish between free and bound morphemes. The word "unhappiness" has three morphemes: un, happi, ness. See https://www.oxfordreference.com/view/10.1093/oi/authority.20110803100210358

3) Graphemes: a minimal unit of writing; also defined as "a written symbol that is used to represent speech." Some writers stress the contrastive element of graphmes: see https://www.thoughtco.com/what-is-a-grapheme-1690916

4) Lexemes: a fundamental and abstract lexical unit of a language. An example is the English lexeme, RUN, whose forms are run, runs, ran, and running. See https://dbpedia.org/page/Lexeme

5) Sememes: the fundamental unit of meaning that a morpheme bears. In the word, "doer," -er is the sememe; the pluralizing unit of meaning -s is another sememe (e.g., doers, writers, linguists).

Pronouncing Pneuma

I would not say that it's wrong to pronounce πνεῦμα without the 'p,' (i.e., "neuma"); it's more a matter of linguistic convention and illustrates how phonemes come to be pronounced in another language. A variety of English dictionaries include pneuma--you can see their pronunciation schemes here:

https://www.onelook.com/?w=pneuma&ls=a

For example, Merriam-Webster has ˈnü-mə for pneuma. Other works give comparable ways of pronouncing the word.

However, when it comes to the Greek, William Mounce writes:

Remember, in Greek there are no silent consonants, so the pi is pronounced; unlike in English where, for example, the "p" is not pronounced in the word, "pneumatic."

See https://www.billmounce.com/greekvocabulary/%CF%80%CE%BD%CE%B5%E1%BF%A6%CE%BC%CE%B1

Either way, I'm not going to castigate or flog anyone who pronounces pneuma without the labial voiceless plosive.