The Oxford Dictionary API give you access to dictionary content in multiple languages including English, Spanish, Urdu, Malay and more.
The terms of service can be found here https://developer.oxforddictionaries.com/api-terms-and-conditions
You will need to sign up to the service to retrieve your app key and ID https://developer.oxforddictionaries.com/?tag=#plans
You will then be able to find your application details here https://developer.oxforddictionaries.com/admin/applications
Data can then be requested with the
app_key and the
curl -X GET --header "Accept: application/json" --header "app_id: 02a1491e" --header "app_key: e6a643b2e3b847760024c00959dc0e69" "https://od-api.oxforddictionaries.com:443/api/v1/entries/en/ace"