形容詞 periodic:

1. happening or recurring at regular intervals
   同義詞：periodical
2. recurring at regular intervals
3. recurring or reappearing from time to time

1. The quality or state of being periodic; recurrence at regular intervals.
   周期性周期出現(xiàn)的性質(zhì)或狀態(tài); 以固定的間隔而發(fā)生
2. A column in the periodic table of the elements.
   屬，族元素周期表上的一欄
3. Russian chemist who first devised and published the periodic table of the elements(1869).
   門捷列夫，季米特里·伊凡諾維奇1834－1907俄國化學(xué)家，是第一個(gè)設(shè)計(jì)并出版元素周期表的人(1869年)
4. The doctor made periodic visit to the house to see if the baby was all right.
   醫(yī)生定期到這家進(jìn)行拜訪，檢查嬰兒有沒有問題。

pe.ri.od.ic

adj.（形容詞）
Having or marked by repeated cycles.
周期的，周期性的：循環(huán)往復(fù)的或以此為特征的
Happening or appearing at regular intervals.
定時(shí)的：在一定間歇期出現(xiàn)或發(fā)生的
Recurring or reappearing from time to time; intermittent.
間歇性的：不時(shí)重復(fù)發(fā)生或出現(xiàn)的；間歇的
Characterized by periodic sentences.
完句的：以循環(huán)句子為特征的

【引伸】
pe.riod.ically
adv.（副詞）
<參考詞匯><同義詞>periodic,sporadic,intermittent,occasional,fitfulThese adjectives all mean recurring or reappearing now and then.Somethingperiodic occurs at regular or at least generally predictable intervals:
這些副詞都意為不時(shí)重復(fù)出現(xiàn)的。某物為periodic ，是指發(fā)生在有規(guī)律的或至少通?？深A(yù)料的間歇里：
例句：
periodic feelings of anxiety.
周期性焦慮。

Sporadic implies appearance or occurrence in scattered, irregular, unpredictable, or isolated instances:
Sporadic 指在雜亂的、不規(guī)律的、無法預(yù)測的或獨(dú)立的情況下出現(xiàn)或發(fā)生：
例句：
a city subjected to sporadic bombing raids.
遭受零星轟炸的城市。

Intermittent describes something that stops and starts at intervals:
Intermittent 描述間歇性開始或停止的事：
例句：
intermittent rain showers. What isoccasional happens at random and irregularly:
間歇性暴雨。 Occational 形容隨機(jī)、無規(guī)律發(fā)生的事情：

例句：
occasional outbursts of temper. Somethingfitful occurs in spells and often abruptly:
感情的突然爆發(fā)。 Fitful 的事發(fā)生在很短的時(shí)間中且常是突然的：

例句：
fitful bursts of energy.
能量的突然爆發(fā)期

Periodic has long been used loosely to mean .occasional, intermittent,. but this usage may be confusing for readers who are accustomed to using the word only in its narrower sense of .at regular or predictable intervals..Thus the writer who saidParker`s losses at the track were not covered by his periodic winners invited the (most likely unintended) inference that Parker had a system that enabled him to pick winners at regular intervals. Substitution ofoccasional in this context would have resolved the ambiguity.
Periodic 長時(shí)間以來不嚴(yán)謹(jǐn)?shù)赜糜谥?時(shí)常的，偶而的.， 但這個(gè)用法常常使那些習(xí)慣于將這個(gè)詞用于.在有規(guī)律或可預(yù)測的間歇內(nèi).這個(gè)狹窄詞義的讀者迷惑。因此寫帕克在賽跑中的失敗不如他的勝利多 這句話的作者（主要是無意中）造成帕克有在定期贏得比賽的方法的推論。 在上下文中用occasional 代替應(yīng)該能解決這種模棱兩可的問題