Sefaria's Tanakh contains a built in lexicon. Double click on a word and the dictionary entry will appear in the side panel. Students can work with a Hebrew text and consult the dictionary -- all within the same screen.
Here's how to use this feature:
In the example below, we are looking up the word "אחרי" in Joshua 1:1
1. Click on the verse to open the panel on the right.
2. Double click on the word you would like to look up. The lexicon will display in the panel on the right, above the connections.