epoch
gb/ˈɛpək/ us/ˈɛpək/
C1
英语
~ 26200
义项
0 个义项
名词
formal
C1
entity
1
distinct historical or personal period
A long, clear period of time in history or in a person's life, often with special or important events.
用法模式：
an epoch in [history / someone's life]
常见错误：
Learners often use 'epoch' in everyday conversation where 'time' or 'period' sounds more natural; 'epoch' is usually used in more formal or serious contexts (history, big life changes). It is also sometimes confused with 'epic' (which describes something grand or heroic) or mispronounced as /ˈiː.pɒk/ instead of /ˈep.ək/.
近义词
era (More common and slightly less formal; often interchangeable, but 'epoch' can sound more weighty or grand.)
|
age (Can sound broader or looser (e.g. 'the age of steam'); 'epoch' suggests a more clearly defined period.)
|
period (Very general and neutral; lacks the sense of importance or distinctiveness that 'epoch' often has.)
反义词
moment (Refers to a very short point in time, contrasting with the long stretches of time suggested by 'epoch'.)
搭配
a new epoch
|an epoch in history
|the modern epoch
|in this epoch
|an epoch in his life
|an epoch of change
主题
history
|society
|culture
|time
|core_vocabulary
例句
- The invention of the internet marked a new epoch in human communication.
- Historians see the collapse of the Soviet Union as the end of an epoch in European politics.
- Her move abroad was an epoch in her life that changed her outlook completely.
- The book explores an epoch of rapid industrial growth and social upheaval.
- We are living in an epoch defined by digital technology and global connectivity.
学习者例句
- The birth of their first child was a new epoch in their life.
- Some people say we are in an epoch of fast change.
- The fall of the old king began a different epoch in that country.
- This film shows an important epoch in the city’s history.
- The war created a dark epoch for many families.
名词
technical
C1
entity
2
geological time subdivision
In geology, a named part of Earth’s history, smaller than a period and bigger than an age.
用法模式：
[the X] epoch
常见错误：
Learners sometimes treat 'epoch', 'era', and 'period' as interchangeable in scientific contexts. In geology they have specific sizes and positions in the time scale, so they should not be swapped when talking about formal geological names.
近义词
geological epoch (A more explicit term that makes clear the technical, scientific context.)
|
era (Sometimes used loosely in popular writing, but in formal geology it refers to a much larger span than an epoch.)
搭配
the Holocene epoch
|the Pleistocene epoch
|the Jurassic epoch (informal)
|during this epoch
|throughout the epoch
|geological epoch
主题
science
|geology
|earth
|nature
例句
- Climate scientists argue that human activity has effectively created a new geological epoch, the Anthropocene.
- The Holocene epoch began approximately 11,700 years ago after the last major ice age.
- Many large mammals went extinct at the end of the Pleistocene epoch.
- These rock layers were formed during the same geological epoch.
- Fossil evidence helps geologists distinguish one epoch from another within a single period.
学习者例句
- The dinosaurs lived in a different epoch from humans.
- Scientists say we may be in a new epoch because of climate change.
- This fossil is from the Holocene epoch.
- Geologists divide Earth’s history into eras, periods, and epochs.
- Many animal types changed between one epoch and the next.
名词
technical
C1
entity
3
reference start time in computing
In computing, a fixed date and time that computers use as a starting point to count time.
用法模式：
the [Unix/system] epoch
常见错误：
Learners sometimes confuse this technical meaning with the general historical sense and try to say things like 'the epoch of computers' when they really mean 'era'. In programming, 'epoch' almost always refers to a specific reference time used for timestamps.
近义词
reference time (General term for any base time point; 'epoch' is the standard technical word in many systems.)
|
zero time (Informal way programmers sometimes refer to the epoch as the point from which counting starts.)
搭配
the Unix epoch
|seconds since the epoch
|time since the epoch
|system epoch time
|epoch timestamp
|Unix epoch time
主题
technology
|computing
|time
例句
- Unix time stores dates as the number of seconds since the Unix epoch.
- If the system clock is set before the epoch, some timestamps may appear as negative values.
- The library converts human-readable dates into milliseconds from the epoch.
- This bug only appears when the timestamp is close to the epoch.
- On many platforms, the epoch is defined as midnight UTC on January 1, 1970.
学习者例句
- In Unix systems, the epoch is January 1, 1970.
- The program shows the number of seconds since the epoch.
- The database saves each date as time from the epoch.
- If the clock is before the epoch, the time value can be wrong.
- We use the same epoch on all servers to avoid errors.
名词
technical
C1
event
4
full pass through training data
In machine learning, one epoch is when the model sees all training examples one time.
用法模式：
[train] for [number] epochs
常见错误：
Learners sometimes think 'epoch' and 'iteration' always mean the same thing in machine learning. In many libraries, an epoch is one full pass through the dataset, while an iteration may refer to a smaller update step, such as one batch.
近义词
training pass (Informal description of the same idea; less standard as a technical term than 'epoch'.)
|
iteration (More general term for a repeated step; in some frameworks, several iterations make up one epoch.)
搭配
train for 10 epochs
|after several epochs
|epoch number
|validation loss per epoch
|complete an epoch
|epoch-based training
主题
technology
|computing
|education
|science
例句
- The model started to overfit after about 30 epochs of training.
- We saved a checkpoint at the end of each epoch to track performance.
- Validation accuracy improved rapidly during the first few epochs, then leveled off.
- Training for more epochs did not significantly reduce the loss.
- They compared the model’s accuracy at the tenth epoch across different architectures.
学习者例句
- The model trains for 20 epochs.
- After each epoch, we check the test score.
- In the first epoch, the loss is usually high.
- The accuracy gets better after many epochs.
- We stop training when the last epoch shows no improvement.
名词
technical
C2
entity
5
astronomical reference date and time
In astronomy, a fixed date and time used as a starting point to describe where a planet or star is in the sky.
用法模式：
[orbital elements] at epoch [date/time]
常见错误：
Learners may confuse this sense with the computing 'epoch' and think they both always refer to 1970. In astronomy, the epoch is any chosen reference date, commonly something like J2000.0, and is not fixed across all systems.
近义词
reference date (General description; 'epoch' is the precise technical term in astronomical data.)
搭配
coordinates at epoch J2000.0
|orbital elements at epoch
|epoch of observation
|position at the chosen epoch
|epoch reference frame
|precessed to the epoch
主题
science
|astronomy
|space
例句
- The star catalog lists positions reduced to the standard epoch J2000.0.
- Orbital elements are usually given for a specific epoch to account for gradual changes over time.
- You must specify the epoch when entering coordinates into the software, or the telescope may point slightly off target.
- These values are valid only near the epoch provided by the observatory.
- Because of precession, the same coordinates refer to different points on the sky at different epochs.
学习者例句
- Astronomers give star positions for a standard epoch.
- The software asks for the epoch of your data.
- Planet orbits slowly change, so we must say the epoch.
- These numbers are correct only near that epoch.
- The catalog uses J2000.0 as its epoch.