1.
grandfather
One's grandfather or someone else's grandfather.
2.
elderly man, old man
An older gentleman.
おじいさん refers to grandfather or elderly men in general.
FORMALITY LEVELS:
- おじいちゃん: grandpa (casual/affectionate)
- おじいさん: grandfather (polite)
- 祖父: grandfather (humble, formal)
- お祖父さん: grandfather (very polite)
MEANINGS:
1. One's own grandfather or someone else's
2. An elderly man in general
CONTRAST WITH SIMILAR WORDS:
- おじいさん: grandfather / elderly man
- おじさん: uncle / middle-aged man
- おばあさん: grandmother / elderly woman
- おばさん: aunt / middle-aged woman
IN FOLKLORE:
昔話 (folktales) often begin with おじいさんとおばあさんがいました (There lived an old man and an old woman).
USAGE NOTE:
When addressing strangers, おじいさん can be used for elderly men but may be considered slightly rude in formal contexts.