Intercourse Not According to Her Custom
Sexual relations that are not in the natural manner, exceptional sexual relations.
"And he shall lie with her according to her custom, and he shall force her - not according to her custom" - Rashi on Genesis 34:2; and similarly: "A widow married to her husband, who is not according to her custom, from where is it that here it is not disqualified as adultery?" - Rashi on Yevamot 59b.
Translation
Expression (Hebrew)
בְּעִילָה שֶׁלֹּא כְּדַרְכָּהּ
Definition (Hebrew)
יַחֲסֵי מִין שֶׁלֹּא בַּצּוּרָה הַטִּבְעִית, יַחֲסֵי מִין חֲרִיגִים.
("וְיִשְׁכַּב אוֹתָהּ-כְּדַרְכָּהּ,וִיעֵנֶיהָ- שֶׁלֹּא כְּדַרְכָּהּ"- רָשִׁ"י בִּבְרֵאשִׁית לֵד ב, וְכֵן:"יְתוֹמָה הַנִּשֵּׂאת לַבַּעַל וּבַעֲלָהּ שֶׁלֹּא כְּדַרְכָּהּ וּמֵאֲנָה בּוֹ דְּאִין כָּאן פְּסוּל זְנוּת"- רָשִׁ"י יְבָמוֹת נט ע"ב)