vow, swear, pledge
誓う（ちかう）、宣誓（せんせい）
to vow, oath
On-reading (セイ) is used in compounds; kun-reading (ちか(う)) is used standalone or with okurigana. Has multiple meanings (vow; swear; pledge). Context determines which applies — pay attention in reading passages. This kanji forms verbs/adjectives with okurigana. Practice both the word form and compound forms.
