When the earliest Christians (the authors of the Bible and their immediate successors) wanted to explain the nature of Jesus to the Greco-Roman world, they picked a word packed with meaning–Word:
 In the beginning was the Word, and the Word was with God, and the Word was God.  He was in the beginning with God.  All things were made through him, and without him was not any thing made that was made.  In him was life, and the life was the light of men.  The light shines in the darkness, and the darkness has not overcome it. (John 1:1–5)
Logos (Λόγος) is the Greek behind the translation of Word
What the ESV translates as Word, is the Greek word Logos (λόγος): “Logos is the Greek term translated as ‘word,’ ‘speech, ‘principle,’ or ‘thought.’ In Greek philosophy, it also referred to a universal, divine reason or the mind of God (source).
Greek Philosophy was not simply about ivory tower contemplation. It was a way of living and thinking about the world. Philosophy was something for every citizen to be concerned with. The Encyclopedia Britannica summarizes the development of logos thought in ancient Greece. The earliest written evidence we have is from the thought of “the 6th-century-BC philosopher Heracleitus, who discerned in the cosmic process a logos analogous to the reasoning power in man.”
How Logos (Word) Developed Through History
What this power was, was perhaps not entirely clear in Heraclitus. The idea of a cosmic process of reason developed, over time, in several distinct directions. On the one hand, there were the Stoics:
These philosophers, who followed the teachings of the thinker Zeno of Citium (4th–3rd century BC), defined the logos as an active rational and spiritual principle that permeated all reality. They called the logos providence, nature, god, and the soul of the universe, which is composed of many seminal logoi that are contained in the universal logos.
Others moved in a more theistic way:
Philo of Alexandria, a 1st-century-AD Jewish philosopher, taught that the logos was the intermediary between God and the cosmos, being both the agent of creation and the agent through which the human mind can apprehend and comprehend God. According to Philo and the Middle Platonists, philosophers who interpreted in religious terms the teachings of the 4th-century-BC Greek master philosopher Plato, the logos was both immanent in the world and at the same time the transcendent divine mind.
Whichever direction they travelled in your thinking, every educated Greek was well versed in the idea of the logos behind Creation. When John presented Jesus, as the Logos, “[become] flesh [to dwell] among us” (John 1:14), he was making a profound, if shocking statement. However, as the Encyclopedia explains, this was a very biblically rooted idea:
This identification of Jesus with the logos is based on Old Testament concepts of revelation, such as occurs in the frequently used phrase “the Word of the Lord”—which connoted ideas of God’s activity and power—and the Jewish view that Wisdom is the divine agent that draws man to God and is identified with the word of God.