Correct spelling


Correct spelling, explanation: this word and the rules behind its spelling seems to be problematic thing. The correct form is equipped, with double p, but it may be confusing because the rule says that we double the last consonant in case of consonant-vowel-consonant combination. The explanation here is that vowel u sometimes acts like a consonant, for example when it comes after the letter q. Therefore in the correct form equipped this vowel is traded like a consonant and thus p is doubled. At the same time equiped is an incorrect form.

Definition of equipped:
verb, past simple and past participle form of equip, to make ready with supplies, to furnish
Have you equipped our van for the trip already?
adjective, to be fully furnished, dressed, etc.
We offer a fully equipped apartment for summer.

Incorrect spelling


Incorrect spelling, explanation: at the first glance it seems like equipped should be spelled with one p: equiped, because the base word equip ends with two vowels and a consonant (so there is no need to double it). However vowel u is treated like a consonant when it comes after q. This is why we double the p in equipped.