Correct spelling, explanation: hiding is the present participle of the verb hide. It is used for continuous tenses, as a noun (gerund), or as an adjective. The present participle form (hiding) is created by adding -ing to the base verb. This is the standard rule for most English verbs. Why not hidding? In English, when forming the present participle: double the final consonant if the verb ends in a single vowel followed by a single consonant and the last syllable is stressed. Do not double the consonant if the final syllable is not stressed, or if the vowel-consonant pattern is absent. Hiding is the only correct form.

Definition of hiding:
1. Verb (present participle), put or keep out of sight
The children were hiding under the table during the game of hide-and-seek.
She is hiding the surprise gift in her closet until the party.
2. Noun (gerund), the situation of being in a place where you cannot be found
Hiding in the attic was their only chance to avoid being caught.
The cat’s hiding made it hard for us to find her during the storm.

Collocations with hiding:
Some of the most commonly used collocations include:
1. In hiding: to be concealed or in a secret location to avoid being found.
The fugitive has been in hiding since he escaped from prison.
2. Hiding place: a location where someone or something is concealed.
The attic was the perfect hiding place for their old treasures.
3. Hiding from: the act of staying out of sight to avoid a person, situation, or danger.
He was hiding from his responsibilities by avoiding his emails.
4. Take a hiding (informal): to be defeated or suffer significant loss or punishment.
Their team took a hiding in last night’s match, losing 5–0.

Incorrect spelling, explanation: you can’t spell hiding as hidding because it doesn’t follow English spelling rules for forming the present participle or gerund of the verb hide. If the verb ends in a silent -e (like hide), drop the -e before adding -ing. In English, we double the final consonant before adding -ing if the verb ends in a single vowel + single consonant or the last syllable is stressed. However, hide ends in a silent -e, so the single vowel + consonant rule doesn’t apply. It’s a single-syllable word, so there’s no stress shift to consider. This means hiding is correct, and hidding violates these conventions.