Dread traces to the Old English verb ondrǣdan (to fear or counsel against).  This evolved through Middle English as dreden, which originally meant to "set the mind against" or "advise against" something.  Over centuries the concept of mentally bracing against impending danger or an opposing force shifted into the meaning of anticipatory terror or deep awe.  The word dread was also used when creating the related words dreadful and dreadlocks.  

According to the Oxford English Dictionary (OED), the word "dread" first appeared in the English language during the Middle English period (1150-1500).  The earliest recorded usage depends on whether the word is used as a verb or a noun: Verb: The earliest evidence for the verb is from around 1175 in the Lambeth Homilies.  Noun: The earliest known use of the noun form dates to around 1200 in the Trinity College Homilies.  According to the OED, the earliest known use of the word dreadful in English dates to around 1225.  And according to the OED, the term "dreadlocks", a compound of "dread" (the emotion of fear or awe) and "locks" (a tress of hair). first emerged in the 1960s. The earliest documented evidence of the word is from 1960 and is found in a text by M. G. Smith and colleagues. 

Dread is the anticipation of an inevitable, negative outcome. Rather than the sudden shock of a jump-scare or gore, dread operates as a slow burn. It is the most powerful tool for hooking audiences because it exploits the imagination, forcing readers to actively participate in building the suspense.   

The Core Importance of dread:  
Subverts the "Unknown": Unlike horror, which relies on confronting a visible monster, dread thrives on the unseen threat. It plays on primal fears, keeping the audience uncertain about what is coming, when it will arrive, or what form it will take.  
Deepens Empathy: By lingering in a character's mind, dread puts the audience in their shoes. Audiences don't just watch a character face danger; they experience the emotional weight of anticipating it.  
Enhances Plot Pacing: Dread acts as emotional scaffolding. By delaying action and focusing on quiet, creeping unease, you create tension that makes any eventual reveal or climax hit much harder.  
Psychological Resonance: It tackles deep-seated, universal fears—like loss, paranoia, and the fragility of our sense of safety. This taps into the primal power of stories that evoke yearning and dread.  

Practical Techniques to Build Dread:  
Control Pacing: Stretch out time. Focus on tiny anomalies, shifting shadows, and sensory details (uncomfortable quiet, strange noises, mundane objects behaving strangely).  
Show the Aftermath First: Let your audience get ahead of the characters. Giving a hint of what is to come or who is in danger builds unbearable anticipation.  
Leverage Restraint: Restraint is power. The brain is almost always scarier than the monster you can physically describe. 

Just the facts:

DREAD Definition & Meaning - Merriam-Webster

DREAD Synonyms: 219 Similar and Opposite Words | Merriam-Webster Thesaurus

DREADFUL Definition & Meaning - Merriam-Webster

DREADLOCK Definition & Meaning - Merriam-Webster