Biweekly和Bimonthly这两个词都可以分别指：

表示“每两周（月）一次”或者“每周（月）两次”都可以用biweekly和bimonthly表达。

以Biweekly为例：

①每两周一次的，A biweekly event or publication happens or appears once every two weeks.

He used to see them at the biweekly meetings.

他过去常常在每两周一次的会议上见到他们。

...Beverage Digest, the industry's biweekly newsletter.

…《饮料文摘》，该行业的双周简讯。

②每周两次的。此时相当于[semiweekly]

The group meets on a regular basis, usually weekly or biweekly.

该小组定期会面，通常每周或每两周一次。

以Bimonthly为例：

①每两月一次的，A bimonthly event or publication happens or appears once every two months.

…bimonthly assemblies.

…两月一次的聚会。

This journal is bimonthly, and that one quarterly.

这本杂志是双月刊，那本是季刊。

②每月两次的，此时相当于[semimonthly]

I use my bimonthly weigh-in results to get information about my nutrition as well.

我还会用每月两次的称重结果来获得有关营养方面的信息。

参考双语例句：

Regular operations, upon request and when possible, by troops and United Nations police to assist the Haitian Maritime Police in conducting coastal patrols, and weekly joint military/United Nations police operations and biweekly joint operations by United Nations police and the Haitian National Police to assist the Haitian National Police in conducting patrols and operations against suspected criminals.

军事部队和联合国警察视需求和情况许可开展常规行动，以协助海地海事警察部队进行海岸巡逻、每周开展一次军事/ 联合国警察的联合行动和每两周开展一次联合国警察和国家警察部队的联合行动，以协助海地国家警察部队开展巡逻和针对犯罪嫌疑人采取行动。

To this end, the AU Commission, with the support of UNOAU, has established a biweekly video conference with AMISOM and UNSOA (Nairobi) and AMISOM (Mogadishu) to continuously engage all stakeholders on the implementation of the operational benchmarks and related activities.

为此，非盟委员会在联非盟办的支持下，已经与非索 特派团和非索特派团支助办(内罗毕)及非索特派团(摩加迪沙)建立了一个举行双周视频会议制度，让所有利益攸关方不断讨论业务基准和相关活动的实施情况。

In this connection it should be noted that the IHP-approved strategy for UNESCO’s category 1 and category 2 water-related centres already provides for networking and partnerships between the institutes and centres and other members of the UNESCO family, including a linkage of websites with UNESCO’s water portal websites and a dissemination of information through the UNESCO water portal bimonthly newsletter.

与此相关，这里顺便提一下国际水文计划的做法，批准的教科文组织有关水问题的1类和2类中心战略，为在这些机构和中心之间以及与教科文组织大家庭其它成员之间建立工作网络和缔结合作伙伴的目的，已经把这些中心名单公布，同时也把它们的网站与教科文组织水文门户网站实现链接并通过该门户网站的双月简讯栏目发布它们的信息。