# prefill

/ˌpɹiˈfɪl/ (US)

Source: https://englishreference.com/word/prefill
Updated: 2026-09-30

## Senses

### 1. to fill in a form ahead of time

verb · CEFR B2

to fill in information on a form or document before you give it to someone. This is often done by a computer to save you time.

For teachers: to populate fields in a digital form or document with data before it is presented to the user. Often describes automated processes that use existing database records to streamline data entry.

- The website will prefill your address if you are logged in.
- Modern web browsers can prefill sensitive payment information, provided the user has granted permission to store such data within their encrypted profile.

### 2. an AI model reading a prompt

verb · CEFR B2 · Technical

to read the whole prompt in one pass before an AI model writes its first token. This is the first step of AI inference.

For teachers: In LLM inference, to process all prompt tokens in parallel and compute the key-value cache before generation begins. This phase is compute-intensive and sets how long a user waits for the first token.

- The server will prefill the prompt before the model writes its first word.
- Because the chip can prefill a long prompt in parallel, reading a large document takes far less time per token than writing the answer.

## Examples

- The website will prefill your address if you are logged in.
- To make the checkout process faster, the application will prefill your shipping details using information from your last order.
- Modern web browsers can prefill sensitive payment information, provided the user has granted permission to store such data within their encrypted profile.

## Usage notes

- Transitive — requires a direct object, typically a form, field, or document.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.