Reader's Guide to Women's Studies, Main HQ 1180 .R43 1998. Although titled "Reader's Guide" is more of a one volume dictionary, albeit with several further reading references at the beginning of each entry. Topical and biographical entries.
Women in the Middle Ages, an Encyclopedia, Main HQ 1143 .W643 2004 v. 1-2. Over 300 entries with baisc and in-depth information on individual women and on broad topics relating to the experience of women in Europe and elsewhere between the 2nd and 15th centuries. Guide to related topics near beginning of the book. Extensive bibliographic references follow the articles in two sections: primary sources and secondary sources.
Lawler, Encyclopedia of Women in the Middle Ages, Main HQ 1143 .L38 2001. Both topical and biographical entries, with further reading references.
Women's Studies Encyclopedia, Main HQ 1115 .W645 1989, v. 3. V. 3 has a series of articles on medieval women: (noble/lay, peasants, religious, treatment of rape in literature and law, urban). Some further reading references.
Duby and Perrot, eds. History of Women in the West, Main HQ 1121 .S79513 1992 v. 1-2. A text. V. 1 From Ancient Goddesses to Christian Saints. V. 2 Silences of the Middle Ages. For topic ideas, narrowing them down, and reading up.