This is the 7442nd most frequent Japanese word.
信太
"信太" (Shinda) is a Japanese proper noun, often used as a surname or place name, with "信" meaning "faith" or "belief" and "太" meaning "great" or "thick."
In this sentence, '信太' is used as a proper noun, designating a person's name.
信太は昔からの友人です。
Shinda is a longstanding friend.
Here, '信太' refers to a geographic name, signifying a place.
信太はその地域の地名です。
Shinda is the name of that region.
'信太' refers to a topic of investigation, emphasizing historical studies related to the name 'Shinda'.