This word was indeed built from the prefix »ge-« and something else, but this was many centuries ago. Now this prefix is glued so strong to »-fahr« that »Fahr« without this prefix makes no sense. It is not a valid German word.
»Gefahr« was »gevare« in Middle High German (about 1050 to 1500 AD). The word »vare« (which later turned to »Fahr« before it became extinct in 18th century) had the meanings stalking, deceit, falsehood, fraud, danger and fear.
Here we even have to go back to Old High German (about 450 to 1050 AD) when this words were »ioman« and »nioman.« The negation particle »io« became extinct already during the period of Old High German while »nio« turned into modern »nie« (English: never). The part »man« is the root of the modern word »Mann« (English: man).
The prefixes of these words (Ge-fahr, je-mand, nie-mand) can still be separated in hyphenation, but not because they existed as independent words many centuries ago. The reason they are separated in hyphenation is simply because they are syllables. Syllables are linguistic units with a vowel as the core and some consonants attached to that nucleus. The core of a syllable can also be a diphthong, but never two separate vowels. If you count a diphthong as one vowel, then each vowel in a word is the nucleus of a syllable, with each word having as many syllables as it has vowels. And in hyphenation, you simply separate syllables.
The two parts »hin« and »unter« still exist as distinct words in modern German, but even in this case it is wrong to say, that »hinunter« is a contraction of »hin« and »unter«. When ever in a sentence the words »hin« and »unter« appear by accident behind each other, it is never possible to replace these two words by »hinunter«. And seen from the other side: When ever you have »hinunter« in a correct sentence, it is impossible to replace it by »hin« and »unter«. (Compare: »im« is a contraction of »in + dem«. The word »im« can always be replaced by »in dem«, but »hinunter« can never be replaced by »hin unter.«
But here the prefix »hin-« (like in hinunter, hinein, hinaus, hinüber, ...) has still a distinct meaning. It means: »away from the speaker« (while »her-« like in herunter, herein, heraus, herüber, ... means: »towards the speaker«).
That the first 4 letter give the word »aber« (English: but) is pure coincidence. The word »aberkennen« has absolutely nothing to do with »aber«. Most German native speakers would even not realize that »aber« is at the beginning of »aberkennen«, because the pronunciation is very different:
- aberkennen = [ˈapʔɛɐ̯ˌkɛnən]
- aber = [ˈaːbɐ]
|aber = [ˈaːbɐ]
||aberkennen = [ˈapʔɛɐ̯ˌkɛnən]
|first vowel is long: [aː]
||first vowel is short: [a]
|first consonant is voiced [b]
||first consonant is voiceless [p]
|No additional consonant before the next vowel
||global stop between the first consonant and the next vowel [ʔ]
|one vowel for the two letters "er": [ɐ]
||"er" is pronounced as diphthong [ɛɐ̯]
In »aberkennen« the prefix »ab-« has a meaning (like the prefixes »hin-« and »her-« have meanings, while *»ge-« in »Gefahr« and »je-« in »jemand« have lost any meaning.) It means to remove something (like in »abmontieren« = English »demount«). What is removed here is »Anerkennung« (English: reputation).