CREDOreference - Online reference books including encyclopaedias, dictionaries and thesauri in a wide range of subject areas.
Oxford English Dictionary
Oxford Language Dictionaries - English, French, German, Spanish and Italian
A thesaurus of British archaeology - is ueful for finding alternative terms for your searches
Another similar resource can be found here
The Thesaurus of archaeological site types is a publication by English Heritage with lots of terms connected with monuments you will come across in the literature
This book is a series of essays on every major topic in Anthropology. There is also a print copy.