Site Search 360 - Site Search 360 enhances and improves your built-in CMS or product search with autocompletion, semantic search, filters, facets, detailed analytics, and a whole lot of customization options.
WebberZone Better Search - Better Search is a WordPress plugin that automatically replaces the default WordPress search with an enhanced contextual based search engine
Relevanssi - Relevanssi replaces the standard WordPress search with a better search engine, with lots of features and configurable options.
Search & Filter - Search & Filter for WordPress allows you to build powerful search experiences for your users and customers - help them find the content they are looking for by creating filters for custom fields, taxonomies and more.
Ivory Search - Ivory Search is a WordPress search plugin that improves WordPress Search by providing advanced options to extend search or exclude specific content from search.
Advanced Woo Search - Advanced Woo Search - WordPress ajax search plugin for WooCommerce store. Search in product title, description, excerpt, sku, tags, categories, attributes, custom fields, custom taxonomies.