His father began to lose his memorybitby bit, becoming increasingly forgetful.
他父亲的记忆力开始一点点衰退,变得越来越健忘。
《柯林斯英汉双解大词典》
2
Their launch strategies involved upgrading their phones bitbybit - a better camera, a brighter screen or larger memory - so as to make the "new" device just a little more attractive.