益々(ますます)Increasingly, More and more, Decreasingly, Less and less, Keep -ing

Both 一方だ and ますます express progressive change, but differ in usage. 一方だ follows verbs, often in formal or objective contexts to describe trends, e.g. '物価は上がる一方だ' ('Prices keep rising'). ますます has a similar nuance, but precedes the phrase or sentence, e.g. '彼の人気はますます高まっている' ('His popularity is increasing more and more').

更に and ますます both suggest addition or progression, but with different nuances. 更に emphasizes adding something on top of what already exists, e.g. '更に三人が参加した' ('Three more people joined'). ますます highlights a state intensifying over time, e.g. 'ますます寒くなってきた' ('It's gotten colder and colder').

どんどん and ますます are both adverbs used to describe change over time. どんどん emphasizes rapid progress or sudden development, often in leaps and bounds. ますます focuses on something already in a certain state becoming even more so, and is often used in polite expressions like wishes for continued health or success.

They are similar in that both describe change, but ば〜ほど specifically expresses a proportional relationship between two things, like the English 'the more (A), the more (B)', e.g. 見れば見るほど好きになる ('The more I look, the more I like it.'). In contrast, ますます simply emphasizes continued intensification, e.g. 彼の人気はますます高まっている ('His popularity is steadily rising.')