The Linguistic Origins of English
English is a member of the world’s largest language family, Indo-European. It belongs to the subdivision of the Germanic, and even more specifically, the West Germanic languages, meaning it is most closely related to German and Dutch. However, only 26% of English is of Germanic origin. The remainder of the language is derived from other branches of Indo-European. 29% is derived from Latin (Italic), another 29% from its descendant, French (Romance), and 6% from Greek (Hellenic). Such variety can be attributed to historical events, such as the Roman occupation of Britain, and the Norman Conquest.

How can we identify which words come from which language?
The best approach to this is to break words down into their smallest components: phonemes, graphemes, and morphemes. A phoneme is a singular sound. A grapheme is the written form of a phoneme, and can consist of a single letter or a combination of letters. A phoneme can have multiple graphemes. For example, the phoneme /f/ in the following words all have different graphemes, indicated in bold: fish, dolphin, effort, laugh. Morphemes are the smallest units of meaning in a word, such as roots and affixes. Friend consists of one morpheme, friendly consists of two (friend-ly), and unfriendly consists of three (un-friend-ly). Observing these features help to recognise what language a word is derived from and what it might mean. This article will look at English etymology in relation to two languages, Ancient Greek and Latin.

Ancient Greek
While 6% may seem like a small amount of Hellenic influence, many features of Latin were influenced by Ancient Greek, suggesting that its influence on English is actually more significant than statistics alone might indicate. Although the Greek alphabet is significantly different to the Roman/Latin alphabet used by English, it is still possible to recognise Greek traces in an English word by looking at its graphemes.
Words containing ph and ch often indicate a Greek etymology and are transliterated from phi (φ) and chi (χ). Another potential indicator is the presence of the letter y, from the Greek vowel, upsilon (υ).
These graphemes can help us to identify whether a word is of Greek origin, but they don’t help with understanding the meaning of words. In order to gain insight into a word’s meaning, we must take a look at its morphemes.
Spotting Greek origins in English words:
Prefixes
a-/an- (alpha privative, expresses negation or absence)
hypo- (under)
hyper- (over)
eu- (good)
dys- (bad)
syn-/sym- (with)
pan- (all)
Suffixes:
-phobia (fear of)
-ology (study of)
-graphy (recording of)
-cracy (rule of)
Roots from Greek nouns:
-bio- (life)
-photo- (light)
-demo- (people/community)
-aero- (air)
By examining the morphology of the following words, not only are we able to identify that they are derived from Greek, but we can also piece together some sort of a definition for them:
biology – study of living things
democracy – rule of the people
anaerobic – without oxygen (air)
Latin
As mentioned, Ancient Greek had a significant influence on the Latin language. A vast amount of academic, medical, and scientific terminology found in the English language comes from both of these languages, but it is Latin that beats Greek in terms of its closeness to English, which is unsurprising given that English uses the Latin alphabet. Furthermore, legal language contains lots of Latin terms: pro bono, prima facie, de facto, et cetera (see what I did there?).
Like Greek, Latin has provided English with many morphemes which can help to identify their origin and meaning.* Here are a few:

Prefixes:
con- (with)
circum- (around)
trans- (across)
sub- (under)
re- (back/again)
pro- (forwards/for)
per- (through/thoroughly)
Suffixes:
-tion/-sion (state/quality of)
-ism (state/doctrine of)
-ious (having the character of)
Roots from Latin verbs:
-gress- (step/move)
-spect- (see)
-lat- (carry)
-vert- (turn)
-fect- (do/make)
*Some of these entered English through French but are ultimately derived from Latin. For example, endings -tion/-sion are taken from French, but they themselves come from the Latin endings -tio/sio.
With this information, we can define the following words as such:
translation – carrying across
perfect – made thoroughly
circumspect – looking around
Now, you may be thinking, yeah I OBVIOUSLY know what PERFECT means, but even if the definition of a word seems obvious, it is nevertheless interesting and useful to know its literal meaning according to its etymology. Once you’re able to identify a morpheme in one word, you can transfer this knowledge to other words. You’ve probably been automatically doing this in your head as you’ve been reading, by thinking of and defining words beyond the few examples given. You may have noticed that perfect and circumspect both contain the consonant cluster -ct-, a common occurrence among Latinate words. The more you explore etymology, the more you will notice patterns like this. What’s great is that, even if you don’t know the complete meaning of a word, being able to recognise part of it can give you some sense of what it could mean or where it comes from.
While these examples only scratch the surface of the Ancient Greek and Latin etymology of English, they give you an idea of how to expand your knowledge of this, should you wish to do so. Understanding the origin of words can help to enrich vocabulary, learn a foreign language, and gain a deeper meaning of the words that we use in our everyday lives.
Statistics from:
Finkenstaedt, Thomas; Wolff, Dieter (1973). Ordered Profusion: Studies in Dictionaries and the English Lexicon. C. Winter. P. 119.