Which of the following words has its letters in the English alphabetical order?

A word has its letters in alphabetical order if each letter appears later or at the same position in the alphabet compared to the preceding letter. Let's trace each option:
* Acepots: $\text{A}(1)\to \text{C}(3)\to \text{E}(5)\to \text{P}(16)\to \text{O}(15)$ $\dots$ Here $\text{P}>\text{O}$ fails the ascending order.
* Acerty: $\text{A}(1)\to \text{C}(3)\to \text{E}(5)\to \text{R}(18)\to \text{T}(20)\to \text{Y}(25)$. All letters are strictly in increasing alphabetical order.
* Acerous: $\text{A}(1)\to \text{C}(3)\to \text{E}(5)\to \text{R}(18)\to \text{O}(15)$ $\dots$ Here $\text{R}>\text{O}$ fails.
* Acephal: $\text{A}(1)\to \text{C}(3)\to \text{E}(5)\to \text{P}(16)\to \text{H}(8)$ $\dots$ Here $\text{P}>\text{H}$ fails.

Thus, only “Acerty” satisfies the alphabetical order condition.