Who is HorizonDefine for?

HorizonDefine is a consumer product built for firefox users who want private, contextual vocabulary assistance.

Is HorizonDefine free?

Yes — HorizonDefine is free to use.

What platforms does HorizonDefine run on?

HorizonDefine runs on the web and embeddable surfaces.

Is HorizonDefine still active?

Unverified. HorizonDefine has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.

Who makes HorizonDefine?

HorizonDefine is developed by Orchestra.

How long has HorizonDefine been around?

HorizonDefine first shipped in 2026.

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HorizonDefine

Name: HorizonDefine
Author: Orchestra

mozilla.orgWriting & editing

HorizonDefine is a Firefox browser extension that lets users right-click words on webpages to view AI-generated definitions, etymology, idioms, and example sentences. Its AI runs locally in the browser, so webpage text does not leave the device.

FreeWebEmbeddable

Visit mozilla.org

Overview

7 features

HorizonDefine sits in PulseGate's Writing & editing category. It focuses on looking up vocabulary definitions and usage examples without sending webpage text to a remote service. It is built as a consumer product for firefox users who want private, contextual vocabulary assistance. It is available for free. HorizonDefine is available on the web and embeddable surfaces.

Behind HorizonDefine is Orchestra, and it first shipped in 2026. Key capabilities include context-menu lookup, word definitions, and etymology. The interface is available in 32 languages, including Czech, German, and Greek.

Summary written by a language model from the project’s public pages.

Context-menu lookup
Word definitions
Etymology
Idiom explanations
Example sentences
Local AI inference
Private processing

Built with & integrations

Runs on

BrowserEmbeddable

Trust & compliance

Verified signals

HTTPSPrivacy Policy Terms of ServiceMulti-languageStore-verified publisher

Legal

Indexing history

What PulseGate has recorded for this listing

Indexed26 Aug · 15:09 UTC
HorizonDefine verified via Firefox Add-ons
Source: Firefox Add-ons · Open

Frequently asked questions about HorizonDefine

What is HorizonDefine?: HorizonDefine focuses on looking up vocabulary definitions and usage examples without sending webpage text to a remote service. It is catalogued under Writing & editing on PulseGate.
Who is HorizonDefine for?: HorizonDefine is a consumer product built for firefox users who want private, contextual vocabulary assistance.
Is HorizonDefine free?: Yes — HorizonDefine is free to use.
What platforms does HorizonDefine run on?: HorizonDefine runs on the web and embeddable surfaces.
Is HorizonDefine still active?: Unverified. HorizonDefine has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.
Who makes HorizonDefine?: HorizonDefine is developed by Orchestra.
How long has HorizonDefine been around?: HorizonDefine first shipped in 2026.
What languages does HorizonDefine support?: The interface is available in 32 languages, including Czech, German, and Greek.

At a glance

Pricing: Free
Platforms: Web
First seen: 26 Aug 2026
Built for: Firefox users who want private, contextual vocabulary assistance
Model: B2C
Solves: Looking up vocabulary definitions and usage examples without sending webpage text to a remote service.

Registered as

Firefox Add-ons: horizondefine

Developer

Orchestra

Index record

Indexed: 26 Aug 2026
Lifecycle: Alive
First seen: Aug 2026
Last seen: 26 Aug 2026

Identity audit (13)

Slug: horizondefine-mozilla-org
Lifecycle last checked: 8 Sep 2026
Verification state: Indexed for public listing
Listing state: Listed: yes
Index status: Included in index
Latest evidence snapshot: 26 Aug 2026
Timeline basis: Indexed-at chronology (no inferred launch/funding milestones).
Name from: Derived from the project's own page and URL.
Category from: Recorded source: taxonomy-pass-b.
Summary from: Written by a language model from public pages.
Languages from: Detected by a language model, checked against the page's own declaration.
Last updated: 26 Aug 2026
Canonical URL: https://addons.mozilla.org/en-US/firefox/addon/horizondefine

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