Definition

Happening or occurring about twice a day, typically every 12 hours, like certain tides or celestial events.

Example

The semidiurnal tides rise and fall every 12 hours, creating a regular pattern in the ocean.

Conversation

Did you know that the tides are semidiurnal around here?

Really? I didn't realize they changed that often.

Yeah, it means they come in and out about every 12 hours.

That makes sense! I guess I should pay more attention to the tides.

Synonyms & Antonyms

Root Explanation

Semidiurnal → It is formed from "semi-" (meaning half) and "diurnalis" (from Latin "diurnus", meaning daily). The word "semidiurnal" refers to something that occurs twice a day, or half of a daily cycle.

Memory Tip

Think of 'semi-' meaning half and 'diurnal' relating to daily activities — this helps you remember that 'semidiurnal' describes something that happens twice in one day.

Visually Confused Words