* Vocabulary: A significant portion of English vocabulary, particularly in scientific, technical, and academic fields, is derived directly from Greek. Words like "biology," "psychology," "telephone," "democracy," "philosophy," and thousands more have Greek roots. This is less noticeable in everyday conversation but becomes strikingly apparent when examining specialized terminology.
* Grammar: While the grammatical structures of English and Ancient Greek differ significantly (English is largely analytic, while Ancient Greek was highly inflected), some grammatical concepts show parallels. For example, both languages use articles (a, an, the in English; ὁ, ἡ, τό in Greek), though their usage varies considerably. Also, the concept of tense and aspect in verbs, while expressed differently, exists in both languages.
* Morphology (word formation): English utilizes Greek roots and affixes (prefixes and suffixes) to create new words, often in scientific and technical contexts. Understanding Greek morphology can significantly aid in understanding the meaning of complex English words. For example, "photoelectric" breaks down to "photo" (light) + "electric" (electricity), both with Greek origins.
* Abstract Concepts: The influence of Greek philosophy and thought has left an indelible mark on Western intellectual history and language. Many abstract concepts and ideas we express in English have their origins in Greek thought, and often the words themselves are derived from Greek.
Important Note: It's crucial to distinguish between Ancient Greek and Modern Greek. While Modern Greek has evolved significantly from Ancient Greek, the vocabulary links are still present, though the grammar differs more substantially from English.
In summary, the similarities between English and Greek aren't primarily about direct linguistic descent, but rather about the profound and lasting influence of Greek vocabulary, concepts, and morphology on the development of English, particularly its scientific and academic lexicon. The connection is largely indirect, mediated through Latin and the historical borrowing of terms over centuries.