希腊语源的原生前缀peri-来自希腊介副词peri，意思相当于英语around，about (周围）或near (附近）。它一般与希腊词根相缀合，构成相应的名词，其中很多是科技术语。

下面我们只介绍几个常用的词。

period [ peri- = around 周围；od = a going 走=>“a going around 走了一圈”→]n. ① a complete and repeated length of time 周期 / A month, from new moon to new moon, is a period.从新月到下次新月的一段时间，就是一个周期。②length or portion of time 时期；期间；时代 / We lived in London for a period of time.我们在伦敦住了一段时期。

periodic a. 周期的；定期的

periodical a. 定期的，期刊的  n. 期刊， 杂志

perigee [ peri- = near 近；ge = earth 地球；-e=>“ near the earth 靠近地球”→]n. the point closest to the earth in the orbit of its satellite 近地点 / The speed is greatest at perigee, when the moon is nearest to the earth. 近地点的速度最大，此时月亮最靠近地球。

perigean a. 近地点的

perimeter [ peri- = around 周; meter = measure 尺寸=>“ the measure around some area 某地周围的尺寸 ”→]n. the outer boundary of a figure or area 周围线，周长 / The perimeter of a circle is more than three times its diameter. 圆的周长是直径的3倍多。