noun
first letter; initial letter; capital initial
Refers to the character at the beginning of a word, name, or sentence. In alphabet contexts it can specifically mean the capital letter used at the start.
英語では文の頭文字を大文字にする。
In English, the first letter of a sentence is capitalized.
この会社名
The first letter of this company name is A.
noun
initials; initial letters of a name
Used for the first letters of a person's surname and given name, especially when representing a name with Roman letters.
彼女は姓と名の頭文字を組み合わせてロゴを作った。
She made a logo by combining the initials of her surname and given name.