ruff; ruffled collar
A collar with many small folds or pleats, often seen on historical European clothing or formal wear.
The person in that portrait is wearing a large ruff.
Standard kanji spelling; 襞 means 'pleat' or 'fold'.
Mixed kanji-kana spelling; easier to read than 襞襟.
Compound of 襞 (ひだ, 'pleat') and 襟 (えり, 'collar').