English prefix ac
The ac is a prefix in a set of prefixs with the same rule, the letter a plus a consonant which is the first letter of a root, other examples: ab-,ac-,ad-,af-,ag-,an-,ap-,ar-,as-,at.
accord: ac(to) + cord(heart)
Accord means agreement, be in harmony, reconcile , be of one mind or consistent between two or multiple entities.
The accord or conflict between countries determine peace or war.
The heart follow, comply, according to an agreement, common rules, a treaty, so everyone can lives in harmony. This should be how it make sense.
acclaim:ac(to) + claim(cry, shout)
Shout to someone may be positive or negative, but in acclaim, it's postive, you shout to some because you love or enthusiastic about him or her. The fans acccalim to the performer in a rock band live.