根据英国剑桥大学的解释，Decimate这个字的原意为 “to kill a large number of something, or to reduce something severely”，即毁灭，大量杀戮；大幅削减之意。
但实际上这个字的拉丁文为decem为「十」（ten）之意，同decimal（十进位）的字根相同，因此延伸至占星学后特别是指自某宫位或星座的第 注视的四分相之意，也可称为支配（Overcoming）或「优势四分相」（Superior square）。
都勒斯的《占星诗集》的中就有许多篇幅讨论支配／压制的概念，不过在书中他多数是以Look down (from the tenth house) at /upon （自第十宫往下注视）的说法来阐释:
If Saturn looked down at Jupiter from the square, it will diminish him in his assets and what things he thinks about, and it will come to bad consequences, and his actions will be interrupted, and he will be corrupting to his parents. And in both of the two squares the assets of his parents will be corrupted and toppled, and that will become evil if they exchanged their places, so that Saturn was the one above Jupiter and Jupiter was in the left square of Saturn. But if Jupiter was the one looking down upon Saturn, then it is less for its evil, and his parents will not get exaltation except in some of the households, and there will be a restriction in his assets, with neither wealth nor poverty.
If Jupiter was in the square of Venus, on her right side, it indicates that that native will be a lover of the people, and will benefit because of women, being good in esteem due to [his] livelihood, coming close to God, powerful in his oaths. And if Venus was looking down upon Jupiter, then evil will be spoken of him in his happiness, and a blemish will afflict him from his eagerness for women, loving praise, and pleasure and cleanliness will accompany him; but he will be afflicted in what he tries to do (of work), and through his own actions he will be seen as committing offense, and he will rejoice in whatever good comes to him due to evil, except that he will do evil.