Words with prefix apo-

Apocalypse means in fact "put away the cover", that is "removing the cover", and then things will be revealed (cf "book of Revelations").

Apocryphal means "hidden away", because they are not to be read. In fact, apocryphal Gospels would be extremely dangerous for Christian believers : the one from St-James mentions explicitly that Jesus had brothers and sisters (and not in a symbolic meaning) and married St-Magdalena ; the one by St-Peter, yes, himself, does not mention the Resurrection, etc..

The word does not mean by itself "spurious", but if it was impossible to deny their existence - they were too well known, at least you could deny their authenticity and forbid their reading.

Apogee means "away from earth" and applied initially to the moon.

Apotheosis means "put away to rejoin the gods".

ETC.

You see that "apo" is always used in the consistent meaning of "away, off"

Interesting question.

The explanation that I have worked out (and that is alluded to in your question itself) is as follows:

apocryphal derives from the noun crypt meaning vault. Short of an explosion you cannot do away with a vault. So apo-cryphal here can only mean away/off in the crypt.

apocalypse on the other hand derives from the Greek action verb kalyptein meaning conceal - thus meaning away/off/un conceal or reveal.

In other words apo- modifies a physical object in the first and an action verb in the second.

"Apoptosis" describes cellular senescence, or a natural, programmed cell death, as opposed to necrosis. The former represents an ordered, predictable process of cell death, whereas the latter represents the potential for pathology. The prefix "apo" means to fall away from. The suffix "ptosis" means to droop. What is most remarkable is the mispronunciation of apoptosis. Since the initial p is silent in the ptosis, it is also silent in apoptosis.

OED:

apo-, prefix

Representing Greek ἀπο- off, from, away; quite.

1. In compounds already formed in Greek, or others analogous to them.

2. In modern scientific words, not on Greek analogies, with sense of ‘standing off or away from each other, detached, separate,’ as apo-carpous.

E.g.

apocalypse, Etymology: < Latin apocalypsis, < Greek ἀποκάλυψις, noun of action < ἀποκαλύπτειν to uncover, disclose, < ἀπό off + καλύπτειν to cover.

apodiabolosis, Etymology: < Greek διάβολος devil, on the model of apotheosis. Lowering to the rank of a devil; a making or treating as diabolical.

apodyterium, Etymology: Latin, < Greek ἀποδυτήριον, < ἀποδύειν to put off, undress. The apartment in which clothes were deposited by those who were preparing for the bath or palæstra; hence gen. a dressing-room, a robing-room.