既是

jìshì
  1. is both ...(and...)
  2. since
  3. as
  4. being the case that

CEDICT

  1. (literary) since; as; being that
  2. since; as; being that

Wiktionary

连词。通常用在上半句话的句首，表示前提，后再加以推论。《水浒传》第三三回：「既是恁地，却容易。」《二十年目睹之怪现状》第二二回：「要参他功名，既是无隙可乘，又咽不下这口恶气。」也作「既然」。

重編國語辭典

Entry Composition

1 既 jì
  1. already
  2. since
  3. both... (and...)
=2 是 shì
  1. to be (followed by substantives only)
  2. correct; right; true
  3. (respectful acknowledgement of a command) very well
  4. (adverb for emphatic assertion)
=2 是 shì variant of 是 shì

Related entries

以来 yǐlái since (a previous event)
我去年以來就沒再做了。

I haven't done that since last year.

Source: Tatoeba

以降 yǐjiàng since (some point in the past)
自从 zìcóng
  1. since (a time)
  2. ever since
自从我认识她的时候，我就恨她。

From the moment that I met her, I hated her.

Source: Tatoeba

自打 zìdǎ (coll.) since
打从 dǎcóng
  1. from
  2. (ever) since
既 jì
  1. already
  2. since
  3. both... (and...)
他既高又帅。

He is tall and handsome.

Source: Tatoeba

兹因 zīyīn
  1. (formal) whereas
  2. since
由于 yóuyú
  1. due to
  2. as a result of
  3. thanks to
  4. owing to
  5. since
  6. because
由于下雨，野餐泡汤了。

The picnic was called off because of the rain.

The picnic was cancelled due to the rain.

The picnic was called off because of rain.

The picnic was canceled because of rain.

The picnic was cancelled because of the rain.

Source: Tatoeba

如 rú
  1. as
  2. as if
  3. such as
如你所知。

As you already know.

Source: Tatoeba

为 wéi
  1. as (in the capacity of)
  2. to take sth as
  3. to act as
  4. to serve as
  5. to behave as
  6. to become
  7. to be
  8. to do
  9. by (in the passive voice)
眼見為憑。

To see is to believe.

Source: Tatoeba

伣 qiàn
  1. (old) like
  2. as
如同 rútóng
  1. like
  2. as
死亡就如同做夢一樣。

Death is like dreaming.

Source: Tatoeba

身为 shēnwéi
  1. in the capacity of
  2. as
我為自己身為女人而感到羞恥。

I'm ashamed to be a woman.

Source: Tatoeba

若 ruò
  1. to seem
  2. like
  3. as
  4. if
我若能來就會來。

I'll come if I can.

I will come if I can.

Oh, if I can go, I will.

Source: Tatoeba

作为 zuòwéi
  1. one's conduct
  2. deed
  3. activity
  4. accomplishment
  5. achievement
  6. to act as
  7. as (in the capacity of)
  8. qua
  9. to view as
  10. to look upon (sth as)
  11. to take sth to be
她養一隻鸚鵡作為寵物。

She keeps a parrot as a pet.

Source: Tatoeba