צפה

Abarim Publications' online Biblical Hebrew Dictionary

There are two roots of the form צפה (sph), one of the adjacent form צפן (spn), and one צוף (sup), and although their meanings are distinct there is some obvious overlap. Then there is the root שפן (spn), which may be the same as צפן (spn) but of a variant spelling:

צפה I

The verb צפה (sapa I) exists in cognate languages in the sense of to hope, but in Biblical Hebrew it means to look out or watch. In the word of HAW Theological Wordbook of the Old Testament: "Sapa conveys the idea of being fully aware of a situation in order to gain some advantage or keep from being surprised by an enemy". It's used to describe vigilant watch keeping (Psalm 66:9), or the monitoring of contractors' fidelity to their covenant (Genesis 36:49). A wicked man may spy upon the righteous (Psalm 37:32) but he is "destined" for the sword (Job 15:22).

This verb's derivatives are:

The feminine noun צפיה (sippiya), meaning lookout post (Lamentations 4:17 only).
The masculine noun מצפה (mispeh), meaning watchtower (Isaiah 21:8) or lookout point (2 Chronicles 20:24 only).

צפה II

The verb צפה (sapa II) also occurs in cognate languages and means the same as in Biblical Hebrew, namely to lay out (Isaiah 21:5) but mostly lay over. It's used when items are overlain with wood (1 Kings 6:15), bronze (2 Chronicles 4:9), gold (Exodus 25:11, 1 Kings 6:20), or precious stones (2 Chronicles 3:6).

This verb's derivatives are:

The masculine noun צפוי (sippuy), meaning plating (Exodus 38:17, Numbers 17:3, Isaiah 30:22).
The feminine noun צפית (sapit), meaning rug or carpet (Isaiah 21:5 only; not all translators agree, see the King James for instance).
The feminine noun צפת (sepet), denoting the plated capital of a pillar (2 Chronicles 3:15 only).

צוף

The verb צוף (sup) is thought to mean to flow or overflow but maybe that's not wholly accurate. It occurs only twice in the Bible: in Lamentations 3:54 the prophet observes that waters flowed over his head to the point that he is cut off. And this clearly brings our verb quite close to the verb צפה (sapa II), meaning to overlay. A similar but reversed image is generated in 1 Kings 6:6, where an iron axe head is made to float on top of the waters.

Our verb comes with two derivatives:

The masculine noun צוף (sup), meaning honeycomb (Psalm 19:10 and Proverbs 16:24 only). Dictionaries suggest that the honeycomb was known as a thing from which honey flowed, but it may very well have been known as a place of storage (see the verb צפן, sapan, next) or even as a place of hope (see צפה, sapa I, above). Remember that the word for bee (דברה, deborah, like the name Deborah) is closely related to the word for word (דבר, dabar).
The feminine verb צפה (sapa), meaning outflow (Ezekiel 32:6 only), and note that this noun is spelled the same as the two verbs צפה (sapa) treated above.

צפן

The verb צפן (sapan) means to hide or store up. This verb is used to hide things or persons in order to protect them (Exodus 2:2, Joshua 2:4, Psalm 27:5), to hide them (sins — Jeremiah 16:17) and perhaps in order to amass a wealth (of knowledge — Proverbs 10:14).

This verb comes with the following derivations:

The masculine noun צפין (sapin), said to mean treasure but the only Biblical occurrence, in Psalm 17:14, speaks of God filling the wicked's belly with it. Still, this is probably a metaphor for wealth because they pass their treasures on to their children.
The feminine noun צפון (sapon), meaning north. HAW Theological Wordbook of the Old Testament explains that "in Canaanite mythology the north was considered to be the place for the meeting of the assembly of the gods". Hence Isaiah 14:13 reads how the king of Babylon boasts, "I will sit on the mount of assembly, in the recesses of the north". BDB Theological Dictionary explains that this word connects to the verb meaning to hide because the north was regarded as "the hidden, dark".
The adjective or noun צפוני (seponi), meaning northern or northern one. This word occurs only once, in Joel 2:20 and it isn't clear whether it's an adjective or noun.
The masculine noun מצפון (maspon), meaning amassments or perhaps treasure. It occurs only once, in Obadiah 1:6.

שפן

The root שפן (shapan) isn't used as a verb in the Bible, but judging from similar verbs in cognate languages, it probably meant to hide or be shy or cunning. Some scholars suggest that this verb is really צפן (sapan) in a variant spelling.

Its only extant derivative is the masculine noun שפן (shapan), which refers to some kind of animal, usually translated as a rock-badger or Coney (rabbit), although that interpretation is difficult to maintain as this animal is listed among those that chew cud (Leviticus 11:5, Deuteronomy 14:7). The only additional hints we have about this creature are that it did not have divided hoofs and was therefore considered unclean, and that it lived in rocks (Psalm 104:18, Proverbs 30:26).